Primitive Type slice

A dynamically-sized view into a contiguous sequence, [T].

Contiguous here means that elements are laid out so that every element is the same distance from its neighbors.

See also the std::slice module.

Slices are a view into a block of memory represented as a pointer and a length.

// slicing a Vec
let vec = vec![1, 2, 3];
let int_slice = &vec[..];
// coercing an array to a slice
let str_slice: &[&str] = &["one", "two", "three"];

Slices are either mutable or shared. The shared slice type is &[T], while the mutable slice type is &mut [T], where T represents the element type. For example, you can mutate the block of memory that a mutable slice points to:

let mut x = [1, 2, 3];
let x = &mut x[..]; // Take a full slice of `x`.
x[1] = 7;
assert_eq!(x, &[1, 7, 3]);

It is possible to slice empty subranges of slices by using empty ranges (including slice.len()..slice.len()):

let x = [1, 2, 3];
let empty = &x[0..0];   // subslice before the first element
assert_eq!(empty, &[]);
let empty = &x[..0];    // same as &x[0..0]
assert_eq!(empty, &[]);
let empty = &x[1..1];   // empty subslice in the middle
assert_eq!(empty, &[]);
let empty = &x[3..3];   // subslice after the last element
assert_eq!(empty, &[]);
let empty = &x[3..];    // same as &x[3..3]
assert_eq!(empty, &[]);

It is not allowed to use subranges that start with lower bound bigger than slice.len():

let x = vec![1, 2, 3];
let _ = &x[4..4];

As slices store the length of the sequence they refer to, they have twice the size of pointers to Sized types. Also see the reference on dynamically sized types.

let pointer_size = std::mem::size_of::<&u8>();
assert_eq!(2 * pointer_size, std::mem::size_of::<&[u8]>());
assert_eq!(2 * pointer_size, std::mem::size_of::<*const [u8]>());
assert_eq!(2 * pointer_size, std::mem::size_of::<Box<[u8]>>());
assert_eq!(2 * pointer_size, std::mem::size_of::<Rc<[u8]>>());

Trait Implementations

Some traits are implemented for slices if the element type implements that trait. This includes Eq, Hash and Ord.

Iteration

The slices implement IntoIterator. The iterator yields references to the slice elements.

let numbers: &[i32] = &[0, 1, 2];
for n in numbers {
    println!("{n} is a number!");
}

The mutable slice yields mutable references to the elements:

let mut scores: &mut [i32] = &mut [7, 8, 9];
for score in scores {
    *score += 1;
}

This iterator yields mutable references to the slice’s elements, so while the element type of the slice is i32, the element type of the iterator is &mut i32.

• .iter and .iter_mut are the explicit methods to return the default iterators.
• Further methods that return iterators are .split, .splitn, .chunks, .windows and more.

Implementations

impl<T> Box<[T]>

pub fn new_uninit_slice(len: usize) -> Box<[MaybeUninit<T>]>

Constructs a new boxed slice with uninitialized contents.

Examples

let mut values = Box::<[u32]>::new_uninit_slice(3);

let values = unsafe {
    // Deferred initialization:
    values[0].as_mut_ptr().write(1);
    values[1].as_mut_ptr().write(2);
    values[2].as_mut_ptr().write(3);

    values.assume_init()
};

assert_eq!(*values, [1, 2, 3])

pub fn new_zeroed_slice(len: usize) -> Box<[MaybeUninit<T>]>

🔬This is a nightly-only experimental API. (new_zeroed_alloc #129396)

Constructs a new boxed slice with uninitialized contents, with the memory being filled with 0 bytes.

See MaybeUninit::zeroed for examples of correct and incorrect usage of this method.

Examples

#![feature(new_zeroed_alloc)]

let values = Box::<[u32]>::new_zeroed_slice(3);
let values = unsafe { values.assume_init() };

assert_eq!(*values, [0, 0, 0])

pub fn try_new_uninit_slice( len: usize, ) -> Result<Box<[MaybeUninit<T>]>, AllocError>

🔬This is a nightly-only experimental API. (allocator_api #32838)

Constructs a new boxed slice with uninitialized contents. Returns an error if the allocation fails.

Examples

#![feature(allocator_api)]

let mut values = Box::<[u32]>::try_new_uninit_slice(3)?;
let values = unsafe {
    // Deferred initialization:
    values[0].as_mut_ptr().write(1);
    values[1].as_mut_ptr().write(2);
    values[2].as_mut_ptr().write(3);
    values.assume_init()
};

assert_eq!(*values, [1, 2, 3]);

pub fn try_new_zeroed_slice( len: usize, ) -> Result<Box<[MaybeUninit<T>]>, AllocError>

🔬This is a nightly-only experimental API. (allocator_api #32838)

Constructs a new boxed slice with uninitialized contents, with the memory being filled with 0 bytes. Returns an error if the allocation fails.

See MaybeUninit::zeroed for examples of correct and incorrect usage of this method.

Examples

#![feature(allocator_api)]

let values = Box::<[u32]>::try_new_zeroed_slice(3)?;
let values = unsafe { values.assume_init() };

assert_eq!(*values, [0, 0, 0]);

impl<T, A> Box<[T], A>

where A: Allocator,

pub fn new_uninit_slice_in(len: usize, alloc: A) -> Box<[MaybeUninit<T>], A>

🔬This is a nightly-only experimental API. (allocator_api #32838)

Constructs a new boxed slice with uninitialized contents in the provided allocator.

Examples

#![feature(allocator_api)]

use std::alloc::System;

let mut values = Box::<[u32], _>::new_uninit_slice_in(3, System);

let values = unsafe {
    // Deferred initialization:
    values[0].as_mut_ptr().write(1);
    values[1].as_mut_ptr().write(2);
    values[2].as_mut_ptr().write(3);

    values.assume_init()
};

assert_eq!(*values, [1, 2, 3])

pub fn new_zeroed_slice_in(len: usize, alloc: A) -> Box<[MaybeUninit<T>], A>

🔬This is a nightly-only experimental API. (allocator_api #32838)

Constructs a new boxed slice with uninitialized contents in the provided allocator, with the memory being filled with 0 bytes.

See MaybeUninit::zeroed for examples of correct and incorrect usage of this method.

Examples

#![feature(allocator_api)]

use std::alloc::System;

let values = Box::<[u32], _>::new_zeroed_slice_in(3, System);
let values = unsafe { values.assume_init() };

assert_eq!(*values, [0, 0, 0])

pub fn try_new_uninit_slice_in( len: usize, alloc: A, ) -> Result<Box<[MaybeUninit<T>], A>, AllocError>

🔬This is a nightly-only experimental API. (allocator_api #32838)

Constructs a new boxed slice with uninitialized contents in the provided allocator. Returns an error if the allocation fails.

Examples

#![feature(allocator_api)]

use std::alloc::System;

let mut values = Box::<[u32], _>::try_new_uninit_slice_in(3, System)?;
let values = unsafe {
    // Deferred initialization:
    values[0].as_mut_ptr().write(1);
    values[1].as_mut_ptr().write(2);
    values[2].as_mut_ptr().write(3);
    values.assume_init()
};

assert_eq!(*values, [1, 2, 3]);

pub fn try_new_zeroed_slice_in( len: usize, alloc: A, ) -> Result<Box<[MaybeUninit<T>], A>, AllocError>

🔬This is a nightly-only experimental API. (allocator_api #32838)

Constructs a new boxed slice with uninitialized contents in the provided allocator, with the memory being filled with 0 bytes. Returns an error if the allocation fails.

See MaybeUninit::zeroed for examples of correct and incorrect usage of this method.

Examples

#![feature(allocator_api)]

use std::alloc::System;

let values = Box::<[u32], _>::try_new_zeroed_slice_in(3, System)?;
let values = unsafe { values.assume_init() };

assert_eq!(*values, [0, 0, 0]);

impl<T, A> Box<[MaybeUninit<T>], A>

where A: Allocator,

pub unsafe fn assume_init(self) -> Box<[T], A>

Converts to Box<[T], A>.

Safety

As with MaybeUninit::assume_init, it is up to the caller to guarantee that the values really are in an initialized state. Calling this when the content is not yet fully initialized causes immediate undefined behavior.

Examples

let mut values = Box::<[u32]>::new_uninit_slice(3);

let values = unsafe {
    // Deferred initialization:
    values[0].as_mut_ptr().write(1);
    values[1].as_mut_ptr().write(2);
    values[2].as_mut_ptr().write(3);

    values.assume_init()
};

assert_eq!(*values, [1, 2, 3])

impl [AsciiChar]

pub const fn as_str(&self) -> &str

🔬This is a nightly-only experimental API. (ascii_char #110998)

Views this slice of ASCII characters as a UTF-8 str.

pub const fn as_bytes(&self) -> &[u8]

🔬This is a nightly-only experimental API. (ascii_char #110998)

Views this slice of ASCII characters as a slice of u8 bytes.

impl [u8]

pub const fn is_ascii(&self) -> bool

Checks if all bytes in this slice are within the ASCII range.

pub const fn as_ascii(&self) -> Option<&[AsciiChar]>

🔬This is a nightly-only experimental API. (ascii_char #110998)

If this slice is_ascii, returns it as a slice of ASCII characters, otherwise returns None.

pub const unsafe fn as_ascii_unchecked(&self) -> &[AsciiChar]

🔬This is a nightly-only experimental API. (ascii_char #110998)

Converts this slice of bytes into a slice of ASCII characters, without checking whether they’re valid.

Safety

Every byte in the slice must be in 0..=127, or else this is UB.

pub fn eq_ignore_ascii_case(&self, other: &[u8]) -> bool

Checks that two slices are an ASCII case-insensitive match.

Same as to_ascii_lowercase(a) == to_ascii_lowercase(b), but without allocating and copying temporaries.

pub const fn make_ascii_uppercase(&mut self)

Converts this slice to its ASCII upper case equivalent in-place.

ASCII letters ‘a’ to ‘z’ are mapped to ‘A’ to ‘Z’, but non-ASCII letters are unchanged.

To return a new uppercased value without modifying the existing one, use to_ascii_uppercase.

pub const fn make_ascii_lowercase(&mut self)

Converts this slice to its ASCII lower case equivalent in-place.

ASCII letters ‘A’ to ‘Z’ are mapped to ‘a’ to ‘z’, but non-ASCII letters are unchanged.

To return a new lowercased value without modifying the existing one, use to_ascii_lowercase.

pub fn escape_ascii(&self) -> EscapeAscii<'_>

Returns an iterator that produces an escaped version of this slice, treating it as an ASCII string.

Examples

let s = b"0\t\r\n'\"\\\x9d";
let escaped = s.escape_ascii().to_string();
assert_eq!(escaped, "0\\t\\r\\n\\'\\\"\\\\\\x9d");

pub const fn trim_ascii_start(&self) -> &[u8]

Returns a byte slice with leading ASCII whitespace bytes removed.

‘Whitespace’ refers to the definition used by u8::is_ascii_whitespace.

Examples

assert_eq!(b" \t hello world\n".trim_ascii_start(), b"hello world\n");
assert_eq!(b"  ".trim_ascii_start(), b"");
assert_eq!(b"".trim_ascii_start(), b"");

pub const fn trim_ascii_end(&self) -> &[u8]

Returns a byte slice with trailing ASCII whitespace bytes removed.

‘Whitespace’ refers to the definition used by u8::is_ascii_whitespace.

Examples

assert_eq!(b"\r hello world\n ".trim_ascii_end(), b"\r hello world");
assert_eq!(b"  ".trim_ascii_end(), b"");
assert_eq!(b"".trim_ascii_end(), b"");

pub const fn trim_ascii(&self) -> &[u8]

Returns a byte slice with leading and trailing ASCII whitespace bytes removed.

‘Whitespace’ refers to the definition used by u8::is_ascii_whitespace.

Examples

assert_eq!(b"\r hello world\n ".trim_ascii(), b"hello world");
assert_eq!(b"  ".trim_ascii(), b"");
assert_eq!(b"".trim_ascii(), b"");

impl<T> [T]

pub const fn len(&self) -> usize

Returns the number of elements in the slice.

Examples

let a = [1, 2, 3];
assert_eq!(a.len(), 3);

pub const fn is_empty(&self) -> bool

Returns true if the slice has a length of 0.

Examples

let a = [1, 2, 3];
assert!(!a.is_empty());

let b: &[i32] = &[];
assert!(b.is_empty());

pub const fn first(&self) -> Option<&T>

Returns the first element of the slice, or None if it is empty.

Examples

let v = [10, 40, 30];
assert_eq!(Some(&10), v.first());

let w: &[i32] = &[];
assert_eq!(None, w.first());

pub const fn first_mut(&mut self) -> Option<&mut T>

Returns a mutable reference to the first element of the slice, or None if it is empty.

Examples

let x = &mut [0, 1, 2];

if let Some(first) = x.first_mut() {
    *first = 5;
}
assert_eq!(x, &[5, 1, 2]);

let y: &mut [i32] = &mut [];
assert_eq!(None, y.first_mut());

pub const fn split_first(&self) -> Option<(&T, &[T])>

Returns the first and all the rest of the elements of the slice, or None if it is empty.

Examples

let x = &[0, 1, 2];

if let Some((first, elements)) = x.split_first() {
    assert_eq!(first, &0);
    assert_eq!(elements, &[1, 2]);
}

pub const fn split_first_mut(&mut self) -> Option<(&mut T, &mut [T])>

Returns the first and all the rest of the elements of the slice, or None if it is empty.

Examples

let x = &mut [0, 1, 2];

if let Some((first, elements)) = x.split_first_mut() {
    *first = 3;
    elements[0] = 4;
    elements[1] = 5;
}
assert_eq!(x, &[3, 4, 5]);

pub const fn split_last(&self) -> Option<(&T, &[T])>

Returns the last and all the rest of the elements of the slice, or None if it is empty.

Examples

let x = &[0, 1, 2];

if let Some((last, elements)) = x.split_last() {
    assert_eq!(last, &2);
    assert_eq!(elements, &[0, 1]);
}

pub const fn split_last_mut(&mut self) -> Option<(&mut T, &mut [T])>

Returns the last and all the rest of the elements of the slice, or None if it is empty.

Examples

let x = &mut [0, 1, 2];

if let Some((last, elements)) = x.split_last_mut() {
    *last = 3;
    elements[0] = 4;
    elements[1] = 5;
}
assert_eq!(x, &[4, 5, 3]);

pub const fn last(&self) -> Option<&T>

Returns the last element of the slice, or None if it is empty.

Examples

let v = [10, 40, 30];
assert_eq!(Some(&30), v.last());

let w: &[i32] = &[];
assert_eq!(None, w.last());

pub const fn last_mut(&mut self) -> Option<&mut T>

Returns a mutable reference to the last item in the slice, or None if it is empty.

Examples

let x = &mut [0, 1, 2];

if let Some(last) = x.last_mut() {
    *last = 10;
}
assert_eq!(x, &[0, 1, 10]);

let y: &mut [i32] = &mut [];
assert_eq!(None, y.last_mut());

pub const fn first_chunk<const N: usize>(&self) -> Option<&[T; N]>

Returns an array reference to the first N items in the slice.

If the slice is not at least N in length, this will return None.

Examples

let u = [10, 40, 30];
assert_eq!(Some(&[10, 40]), u.first_chunk::<2>());

let v: &[i32] = &[10];
assert_eq!(None, v.first_chunk::<2>());

let w: &[i32] = &[];
assert_eq!(Some(&[]), w.first_chunk::<0>());

pub const fn first_chunk_mut<const N: usize>(&mut self) -> Option<&mut [T; N]>

Returns a mutable array reference to the first N items in the slice.

If the slice is not at least N in length, this will return None.

Examples

let x = &mut [0, 1, 2];

if let Some(first) = x.first_chunk_mut::<2>() {
    first[0] = 5;
    first[1] = 4;
}
assert_eq!(x, &[5, 4, 2]);

assert_eq!(None, x.first_chunk_mut::<4>());

pub const fn split_first_chunk<const N: usize>(&self) -> Option<(&[T; N], &[T])>

Returns an array reference to the first N items in the slice and the remaining slice.

If the slice is not at least N in length, this will return None.

Examples

let x = &[0, 1, 2];

if let Some((first, elements)) = x.split_first_chunk::<2>() {
    assert_eq!(first, &[0, 1]);
    assert_eq!(elements, &[2]);
}

assert_eq!(None, x.split_first_chunk::<4>());

pub const fn split_first_chunk_mut<const N: usize>( &mut self, ) -> Option<(&mut [T; N], &mut [T])>

Returns a mutable array reference to the first N items in the slice and the remaining slice.

If the slice is not at least N in length, this will return None.

Examples

let x = &mut [0, 1, 2];

if let Some((first, elements)) = x.split_first_chunk_mut::<2>() {
    first[0] = 3;
    first[1] = 4;
    elements[0] = 5;
}
assert_eq!(x, &[3, 4, 5]);

assert_eq!(None, x.split_first_chunk_mut::<4>());

pub const fn split_last_chunk<const N: usize>(&self) -> Option<(&[T], &[T; N])>

Returns an array reference to the last N items in the slice and the remaining slice.

If the slice is not at least N in length, this will return None.

Examples

let x = &[0, 1, 2];

if let Some((elements, last)) = x.split_last_chunk::<2>() {
    assert_eq!(elements, &[0]);
    assert_eq!(last, &[1, 2]);
}

assert_eq!(None, x.split_last_chunk::<4>());

pub const fn split_last_chunk_mut<const N: usize>( &mut self, ) -> Option<(&mut [T], &mut [T; N])>

Returns a mutable array reference to the last N items in the slice and the remaining slice.

If the slice is not at least N in length, this will return None.

Examples

let x = &mut [0, 1, 2];

if let Some((elements, last)) = x.split_last_chunk_mut::<2>() {
    last[0] = 3;
    last[1] = 4;
    elements[0] = 5;
}
assert_eq!(x, &[5, 3, 4]);

assert_eq!(None, x.split_last_chunk_mut::<4>());

pub const fn last_chunk<const N: usize>(&self) -> Option<&[T; N]>

Returns an array reference to the last N items in the slice.

If the slice is not at least N in length, this will return None.

Examples

let u = [10, 40, 30];
assert_eq!(Some(&[40, 30]), u.last_chunk::<2>());

let v: &[i32] = &[10];
assert_eq!(None, v.last_chunk::<2>());

let w: &[i32] = &[];
assert_eq!(Some(&[]), w.last_chunk::<0>());

pub const fn last_chunk_mut<const N: usize>(&mut self) -> Option<&mut [T; N]>

Returns a mutable array reference to the last N items in the slice.

If the slice is not at least N in length, this will return None.

Examples

let x = &mut [0, 1, 2];

if let Some(last) = x.last_chunk_mut::<2>() {
    last[0] = 10;
    last[1] = 20;
}
assert_eq!(x, &[0, 10, 20]);

assert_eq!(None, x.last_chunk_mut::<4>());

pub fn get<I>(&self, index: I) -> Option<&<I as SliceIndex<[T]>>::Output>

where I: SliceIndex<[T]>,

Returns a reference to an element or subslice depending on the type of index.

• If given a position, returns a reference to the element at that position or None if out of bounds.
• If given a range, returns the subslice corresponding to that range, or None if out of bounds.

Examples

let v = [10, 40, 30];
assert_eq!(Some(&40), v.get(1));
assert_eq!(Some(&[10, 40][..]), v.get(0..2));
assert_eq!(None, v.get(3));
assert_eq!(None, v.get(0..4));

pub fn get_mut<I>( &mut self, index: I, ) -> Option<&mut <I as SliceIndex<[T]>>::Output>

where I: SliceIndex<[T]>,

Returns a mutable reference to an element or subslice depending on the type of index (see get) or None if the index is out of bounds.

Examples

let x = &mut [0, 1, 2];

if let Some(elem) = x.get_mut(1) {
    *elem = 42;
}
assert_eq!(x, &[0, 42, 2]);

pub unsafe fn get_unchecked<I>( &self, index: I, ) -> &<I as SliceIndex<[T]>>::Output

where I: SliceIndex<[T]>,

Returns a reference to an element or subslice, without doing bounds checking.

For a safe alternative see get.

Safety

Calling this method with an out-of-bounds index is undefined behavior even if the resulting reference is not used.

You can think of this like .get(index).unwrap_unchecked(). It’s UB to call .get_unchecked(len), even if you immediately convert to a pointer. And it’s UB to call .get_unchecked(..len + 1), .get_unchecked(..=len), or similar.

Examples

let x = &[1, 2, 4];

unsafe {
    assert_eq!(x.get_unchecked(1), &2);
}

pub unsafe fn get_unchecked_mut<I>( &mut self, index: I, ) -> &mut <I as SliceIndex<[T]>>::Output

where I: SliceIndex<[T]>,

Returns a mutable reference to an element or subslice, without doing bounds checking.

For a safe alternative see get_mut.

Safety

Calling this method with an out-of-bounds index is undefined behavior even if the resulting reference is not used.

You can think of this like .get_mut(index).unwrap_unchecked(). It’s UB to call .get_unchecked_mut(len), even if you immediately convert to a pointer. And it’s UB to call .get_unchecked_mut(..len + 1), .get_unchecked_mut(..=len), or similar.

Examples

let x = &mut [1, 2, 4];

unsafe {
    let elem = x.get_unchecked_mut(1);
    *elem = 13;
}
assert_eq!(x, &[1, 13, 4]);

pub const fn as_ptr(&self) -> *const T

Returns a raw pointer to the slice’s buffer.

The caller must ensure that the slice outlives the pointer this function returns, or else it will end up dangling.

The caller must also ensure that the memory the pointer (non-transitively) points to is never written to (except inside an UnsafeCell) using this pointer or any pointer derived from it. If you need to mutate the contents of the slice, use as_mut_ptr.

Modifying the container referenced by this slice may cause its buffer to be reallocated, which would also make any pointers to it invalid.

Examples

let x = &[1, 2, 4];
let x_ptr = x.as_ptr();

unsafe {
    for i in 0..x.len() {
        assert_eq!(x.get_unchecked(i), &*x_ptr.add(i));
    }
}

pub const fn as_mut_ptr(&mut self) -> *mut T

Returns an unsafe mutable pointer to the slice’s buffer.

The caller must ensure that the slice outlives the pointer this function returns, or else it will end up dangling.

Modifying the container referenced by this slice may cause its buffer to be reallocated, which would also make any pointers to it invalid.

Examples

let x = &mut [1, 2, 4];
let x_ptr = x.as_mut_ptr();

unsafe {
    for i in 0..x.len() {
        *x_ptr.add(i) += 2;
    }
}
assert_eq!(x, &[3, 4, 6]);

pub const fn as_ptr_range(&self) -> Range<*const T>

Returns the two raw pointers spanning the slice.

The returned range is half-open, which means that the end pointer points one past the last element of the slice. This way, an empty slice is represented by two equal pointers, and the difference between the two pointers represents the size of the slice.

See as_ptr for warnings on using these pointers. The end pointer requires extra caution, as it does not point to a valid element in the slice.

This function is useful for interacting with foreign interfaces which use two pointers to refer to a range of elements in memory, as is common in C++.

It can also be useful to check if a pointer to an element refers to an element of this slice:

let a = [1, 2, 3];
let x = &a[1] as *const _;
let y = &5 as *const _;

assert!(a.as_ptr_range().contains(&x));
assert!(!a.as_ptr_range().contains(&y));

pub const fn as_mut_ptr_range(&mut self) -> Range<*mut T>

Returns the two unsafe mutable pointers spanning the slice.

The returned range is half-open, which means that the end pointer points one past the last element of the slice. This way, an empty slice is represented by two equal pointers, and the difference between the two pointers represents the size of the slice.

See as_mut_ptr for warnings on using these pointers. The end pointer requires extra caution, as it does not point to a valid element in the slice.

This function is useful for interacting with foreign interfaces which use two pointers to refer to a range of elements in memory, as is common in C++.

pub const fn as_array<const N: usize>(&self) -> Option<&[T; N]>

🔬This is a nightly-only experimental API. (slice_as_array #133508)

Gets a reference to the underlying array.

If N is not exactly equal to the length of self, then this method returns None.

pub const fn as_mut_array<const N: usize>(&mut self) -> Option<&mut [T; N]>

🔬This is a nightly-only experimental API. (slice_as_array #133508)

Gets a mutable reference to the slice’s underlying array.

If N is not exactly equal to the length of self, then this method returns None.

pub fn swap(&mut self, a: usize, b: usize)

Swaps two elements in the slice.

If a equals to b, it’s guaranteed that elements won’t change value.

Arguments

• a - The index of the first element
• b - The index of the second element

Panics

Panics if a or b are out of bounds.

Examples

let mut v = ["a", "b", "c", "d", "e"];
v.swap(2, 4);
assert!(v == ["a", "b", "e", "d", "c"]);

pub const unsafe fn swap_unchecked(&mut self, a: usize, b: usize)

🔬This is a nightly-only experimental API. (slice_swap_unchecked #88539)

Swaps two elements in the slice, without doing bounds checking.

For a safe alternative see swap.

Arguments

• a - The index of the first element
• b - The index of the second element

Safety

Calling this method with an out-of-bounds index is undefined behavior. The caller has to ensure that a < self.len() and b < self.len().

Examples

#![feature(slice_swap_unchecked)]

let mut v = ["a", "b", "c", "d"];
// SAFETY: we know that 1 and 3 are both indices of the slice
unsafe { v.swap_unchecked(1, 3) };
assert!(v == ["a", "d", "c", "b"]);

pub fn reverse(&mut self)

Reverses the order of elements in the slice, in place.

Examples

let mut v = [1, 2, 3];
v.reverse();
assert!(v == [3, 2, 1]);

pub fn iter(&self) -> Iter<'_, T>

Returns an iterator over the slice.

The iterator yields all items from start to end.

Examples

let x = &[1, 2, 4];
let mut iterator = x.iter();

assert_eq!(iterator.next(), Some(&1));
assert_eq!(iterator.next(), Some(&2));
assert_eq!(iterator.next(), Some(&4));
assert_eq!(iterator.next(), None);

pub fn iter_mut(&mut self) -> IterMut<'_, T>

Returns an iterator that allows modifying each value.

The iterator yields all items from start to end.

Examples

let x = &mut [1, 2, 4];
for elem in x.iter_mut() {
    *elem += 2;
}
assert_eq!(x, &[3, 4, 6]);

pub fn windows(&self, size: usize) -> Windows<'_, T>

Returns an iterator over all contiguous windows of length size. The windows overlap. If the slice is shorter than size, the iterator returns no values.

Panics

Panics if size is zero.

Examples

let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.windows(3);
assert_eq!(iter.next().unwrap(), &['l', 'o', 'r']);
assert_eq!(iter.next().unwrap(), &['o', 'r', 'e']);
assert_eq!(iter.next().unwrap(), &['r', 'e', 'm']);
assert!(iter.next().is_none());

If the slice is shorter than size:

let slice = ['f', 'o', 'o'];
let mut iter = slice.windows(4);
assert!(iter.next().is_none());

There’s no windows_mut, as that existing would let safe code violate the “only one &mut at a time to the same thing” rule. However, you can sometimes use Cell::as_slice_of_cells in conjunction with windows to accomplish something similar:

use std::cell::Cell;

let mut array = ['R', 'u', 's', 't', ' ', '2', '0', '1', '5'];
let slice = &mut array[..];
let slice_of_cells: &[Cell<char>] = Cell::from_mut(slice).as_slice_of_cells();
for w in slice_of_cells.windows(3) {
    Cell::swap(&w[0], &w[2]);
}
assert_eq!(array, ['s', 't', ' ', '2', '0', '1', '5', 'u', 'R']);

pub fn chunks(&self, chunk_size: usize) -> Chunks<'_, T>

Returns an iterator over chunk_size elements of the slice at a time, starting at the beginning of the slice.

The chunks are slices and do not overlap. If chunk_size does not divide the length of the slice, then the last chunk will not have length chunk_size.

See chunks_exact for a variant of this iterator that returns chunks of always exactly chunk_size elements, and rchunks for the same iterator but starting at the end of the slice.

Panics

Panics if chunk_size is zero.

Examples

let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.chunks(2);
assert_eq!(iter.next().unwrap(), &['l', 'o']);
assert_eq!(iter.next().unwrap(), &['r', 'e']);
assert_eq!(iter.next().unwrap(), &['m']);
assert!(iter.next().is_none());

pub fn chunks_mut(&mut self, chunk_size: usize) -> ChunksMut<'_, T>

Returns an iterator over chunk_size elements of the slice at a time, starting at the beginning of the slice.

The chunks are mutable slices, and do not overlap. If chunk_size does not divide the length of the slice, then the last chunk will not have length chunk_size.

See chunks_exact_mut for a variant of this iterator that returns chunks of always exactly chunk_size elements, and rchunks_mut for the same iterator but starting at the end of the slice.

Panics

Panics if chunk_size is zero.

Examples

let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;

for chunk in v.chunks_mut(2) {
    for elem in chunk.iter_mut() {
        *elem += count;
    }
    count += 1;
}
assert_eq!(v, &[1, 1, 2, 2, 3]);

pub fn chunks_exact(&self, chunk_size: usize) -> ChunksExact<'_, T>

Returns an iterator over chunk_size elements of the slice at a time, starting at the beginning of the slice.

The chunks are slices and do not overlap. If chunk_size does not divide the length of the slice, then the last up to chunk_size-1 elements will be omitted and can be retrieved from the remainder function of the iterator.

Due to each chunk having exactly chunk_size elements, the compiler can often optimize the resulting code better than in the case of chunks.

See chunks for a variant of this iterator that also returns the remainder as a smaller chunk, and rchunks_exact for the same iterator but starting at the end of the slice.

Panics

Panics if chunk_size is zero.

Examples

let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.chunks_exact(2);
assert_eq!(iter.next().unwrap(), &['l', 'o']);
assert_eq!(iter.next().unwrap(), &['r', 'e']);
assert!(iter.next().is_none());
assert_eq!(iter.remainder(), &['m']);

pub fn chunks_exact_mut(&mut self, chunk_size: usize) -> ChunksExactMut<'_, T>

Returns an iterator over chunk_size elements of the slice at a time, starting at the beginning of the slice.

The chunks are mutable slices, and do not overlap. If chunk_size does not divide the length of the slice, then the last up to chunk_size-1 elements will be omitted and can be retrieved from the into_remainder function of the iterator.

Due to each chunk having exactly chunk_size elements, the compiler can often optimize the resulting code better than in the case of chunks_mut.

See chunks_mut for a variant of this iterator that also returns the remainder as a smaller chunk, and rchunks_exact_mut for the same iterator but starting at the end of the slice.

Panics

Panics if chunk_size is zero.

Examples

let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;

for chunk in v.chunks_exact_mut(2) {
    for elem in chunk.iter_mut() {
        *elem += count;
    }
    count += 1;
}
assert_eq!(v, &[1, 1, 2, 2, 0]);

pub const unsafe fn as_chunks_unchecked<const N: usize>(&self) -> &[[T; N]]

🔬This is a nightly-only experimental API. (slice_as_chunks #74985)

Splits the slice into a slice of N-element arrays, assuming that there’s no remainder.

Safety

This may only be called when

• The slice splits exactly into N-element chunks (aka self.len() % N == 0).
• N != 0.

Examples

#![feature(slice_as_chunks)]
let slice: &[char] = &['l', 'o', 'r', 'e', 'm', '!'];
let chunks: &[[char; 1]] =
    // SAFETY: 1-element chunks never have remainder
    unsafe { slice.as_chunks_unchecked() };
assert_eq!(chunks, &[['l'], ['o'], ['r'], ['e'], ['m'], ['!']]);
let chunks: &[[char; 3]] =
    // SAFETY: The slice length (6) is a multiple of 3
    unsafe { slice.as_chunks_unchecked() };
assert_eq!(chunks, &[['l', 'o', 'r'], ['e', 'm', '!']]);

// These would be unsound:
// let chunks: &[[_; 5]] = slice.as_chunks_unchecked() // The slice length is not a multiple of 5
// let chunks: &[[_; 0]] = slice.as_chunks_unchecked() // Zero-length chunks are never allowed

pub const fn as_chunks<const N: usize>(&self) -> (&[[T; N]], &[T])

🔬This is a nightly-only experimental API. (slice_as_chunks #74985)

Splits the slice into a slice of N-element arrays, starting at the beginning of the slice, and a remainder slice with length strictly less than N.

Panics

Panics if N is zero. This check will most probably get changed to a compile time error before this method gets stabilized.

Examples

#![feature(slice_as_chunks)]
let slice = ['l', 'o', 'r', 'e', 'm'];
let (chunks, remainder) = slice.as_chunks();
assert_eq!(chunks, &[['l', 'o'], ['r', 'e']]);
assert_eq!(remainder, &['m']);

If you expect the slice to be an exact multiple, you can combine let-else with an empty slice pattern:

#![feature(slice_as_chunks)]
let slice = ['R', 'u', 's', 't'];
let (chunks, []) = slice.as_chunks::<2>() else {
    panic!("slice didn't have even length")
};
assert_eq!(chunks, &[['R', 'u'], ['s', 't']]);

pub const fn as_rchunks<const N: usize>(&self) -> (&[T], &[[T; N]])

🔬This is a nightly-only experimental API. (slice_as_chunks #74985)

Splits the slice into a slice of N-element arrays, starting at the end of the slice, and a remainder slice with length strictly less than N.

Panics

Panics if N is zero. This check will most probably get changed to a compile time error before this method gets stabilized.

Examples

#![feature(slice_as_chunks)]
let slice = ['l', 'o', 'r', 'e', 'm'];
let (remainder, chunks) = slice.as_rchunks();
assert_eq!(remainder, &['l']);
assert_eq!(chunks, &[['o', 'r'], ['e', 'm']]);

pub fn array_chunks<const N: usize>(&self) -> ArrayChunks<'_, T, N>

🔬This is a nightly-only experimental API. (array_chunks #74985)

Returns an iterator over N elements of the slice at a time, starting at the beginning of the slice.

The chunks are array references and do not overlap. If N does not divide the length of the slice, then the last up to N-1 elements will be omitted and can be retrieved from the remainder function of the iterator.

This method is the const generic equivalent of chunks_exact.

Panics

Panics if N is zero. This check will most probably get changed to a compile time error before this method gets stabilized.

Examples

#![feature(array_chunks)]
let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.array_chunks();
assert_eq!(iter.next().unwrap(), &['l', 'o']);
assert_eq!(iter.next().unwrap(), &['r', 'e']);
assert!(iter.next().is_none());
assert_eq!(iter.remainder(), &['m']);

pub const unsafe fn as_chunks_unchecked_mut<const N: usize>( &mut self, ) -> &mut [[T; N]]

🔬This is a nightly-only experimental API. (slice_as_chunks #74985)

Splits the slice into a slice of N-element arrays, assuming that there’s no remainder.

Safety

This may only be called when

• The slice splits exactly into N-element chunks (aka self.len() % N == 0).
• N != 0.

Examples

#![feature(slice_as_chunks)]
let slice: &mut [char] = &mut ['l', 'o', 'r', 'e', 'm', '!'];
let chunks: &mut [[char; 1]] =
    // SAFETY: 1-element chunks never have remainder
    unsafe { slice.as_chunks_unchecked_mut() };
chunks[0] = ['L'];
assert_eq!(chunks, &[['L'], ['o'], ['r'], ['e'], ['m'], ['!']]);
let chunks: &mut [[char; 3]] =
    // SAFETY: The slice length (6) is a multiple of 3
    unsafe { slice.as_chunks_unchecked_mut() };
chunks[1] = ['a', 'x', '?'];
assert_eq!(slice, &['L', 'o', 'r', 'a', 'x', '?']);

// These would be unsound:
// let chunks: &[[_; 5]] = slice.as_chunks_unchecked_mut() // The slice length is not a multiple of 5
// let chunks: &[[_; 0]] = slice.as_chunks_unchecked_mut() // Zero-length chunks are never allowed

pub const fn as_chunks_mut<const N: usize>( &mut self, ) -> (&mut [[T; N]], &mut [T])

🔬This is a nightly-only experimental API. (slice_as_chunks #74985)

Splits the slice into a slice of N-element arrays, starting at the beginning of the slice, and a remainder slice with length strictly less than N.

Panics

Panics if N is zero. This check will most probably get changed to a compile time error before this method gets stabilized.

Examples

#![feature(slice_as_chunks)]
let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;

let (chunks, remainder) = v.as_chunks_mut();
remainder[0] = 9;
for chunk in chunks {
    *chunk = [count; 2];
    count += 1;
}
assert_eq!(v, &[1, 1, 2, 2, 9]);

pub const fn as_rchunks_mut<const N: usize>( &mut self, ) -> (&mut [T], &mut [[T; N]])

🔬This is a nightly-only experimental API. (slice_as_chunks #74985)

Splits the slice into a slice of N-element arrays, starting at the end of the slice, and a remainder slice with length strictly less than N.

Panics

Panics if N is zero. This check will most probably get changed to a compile time error before this method gets stabilized.

Examples

#![feature(slice_as_chunks)]
let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;

let (remainder, chunks) = v.as_rchunks_mut();
remainder[0] = 9;
for chunk in chunks {
    *chunk = [count; 2];
    count += 1;
}
assert_eq!(v, &[9, 1, 1, 2, 2]);

pub fn array_chunks_mut<const N: usize>(&mut self) -> ArrayChunksMut<'_, T, N>

🔬This is a nightly-only experimental API. (array_chunks #74985)

Returns an iterator over N elements of the slice at a time, starting at the beginning of the slice.

The chunks are mutable array references and do not overlap. If N does not divide the length of the slice, then the last up to N-1 elements will be omitted and can be retrieved from the into_remainder function of the iterator.

This method is the const generic equivalent of chunks_exact_mut.

Panics

Panics if N is zero. This check will most probably get changed to a compile time error before this method gets stabilized.

Examples

#![feature(array_chunks)]
let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;

for chunk in v.array_chunks_mut() {
    *chunk = [count; 2];
    count += 1;
}
assert_eq!(v, &[1, 1, 2, 2, 0]);

pub fn array_windows<const N: usize>(&self) -> ArrayWindows<'_, T, N>

🔬This is a nightly-only experimental API. (array_windows #75027)

Returns an iterator over overlapping windows of N elements of a slice, starting at the beginning of the slice.

This is the const generic equivalent of windows.

If N is greater than the size of the slice, it will return no windows.

Panics

Panics if N is zero. This check will most probably get changed to a compile time error before this method gets stabilized.

Examples

#![feature(array_windows)]
let slice = [0, 1, 2, 3];
let mut iter = slice.array_windows();
assert_eq!(iter.next().unwrap(), &[0, 1]);
assert_eq!(iter.next().unwrap(), &[1, 2]);
assert_eq!(iter.next().unwrap(), &[2, 3]);
assert!(iter.next().is_none());

pub fn rchunks(&self, chunk_size: usize) -> RChunks<'_, T>

Returns an iterator over chunk_size elements of the slice at a time, starting at the end of the slice.

The chunks are slices and do not overlap. If chunk_size does not divide the length of the slice, then the last chunk will not have length chunk_size.

See rchunks_exact for a variant of this iterator that returns chunks of always exactly chunk_size elements, and chunks for the same iterator but starting at the beginning of the slice.

Panics

Panics if chunk_size is zero.

Examples

let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.rchunks(2);
assert_eq!(iter.next().unwrap(), &['e', 'm']);
assert_eq!(iter.next().unwrap(), &['o', 'r']);
assert_eq!(iter.next().unwrap(), &['l']);
assert!(iter.next().is_none());

pub fn rchunks_mut(&mut self, chunk_size: usize) -> RChunksMut<'_, T>

Returns an iterator over chunk_size elements of the slice at a time, starting at the end of the slice.

The chunks are mutable slices, and do not overlap. If chunk_size does not divide the length of the slice, then the last chunk will not have length chunk_size.

See rchunks_exact_mut for a variant of this iterator that returns chunks of always exactly chunk_size elements, and chunks_mut for the same iterator but starting at the beginning of the slice.

Panics

Panics if chunk_size is zero.

Examples

let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;

for chunk in v.rchunks_mut(2) {
    for elem in chunk.iter_mut() {
        *elem += count;
    }
    count += 1;
}
assert_eq!(v, &[3, 2, 2, 1, 1]);

pub fn rchunks_exact(&self, chunk_size: usize) -> RChunksExact<'_, T>

Returns an iterator over chunk_size elements of the slice at a time, starting at the end of the slice.

The chunks are slices and do not overlap. If chunk_size does not divide the length of the slice, then the last up to chunk_size-1 elements will be omitted and can be retrieved from the remainder function of the iterator.

Due to each chunk having exactly chunk_size elements, the compiler can often optimize the resulting code better than in the case of rchunks.

See rchunks for a variant of this iterator that also returns the remainder as a smaller chunk, and chunks_exact for the same iterator but starting at the beginning of the slice.

Panics

Panics if chunk_size is zero.

Examples

let slice = ['l', 'o', 'r', 'e', 'm'];
let mut iter = slice.rchunks_exact(2);
assert_eq!(iter.next().unwrap(), &['e', 'm']);
assert_eq!(iter.next().unwrap(), &['o', 'r']);
assert!(iter.next().is_none());
assert_eq!(iter.remainder(), &['l']);

pub fn rchunks_exact_mut(&mut self, chunk_size: usize) -> RChunksExactMut<'_, T>

Returns an iterator over chunk_size elements of the slice at a time, starting at the end of the slice.

The chunks are mutable slices, and do not overlap. If chunk_size does not divide the length of the slice, then the last up to chunk_size-1 elements will be omitted and can be retrieved from the into_remainder function of the iterator.

Due to each chunk having exactly chunk_size elements, the compiler can often optimize the resulting code better than in the case of chunks_mut.

See rchunks_mut for a variant of this iterator that also returns the remainder as a smaller chunk, and chunks_exact_mut for the same iterator but starting at the beginning of the slice.

Panics

Panics if chunk_size is zero.

Examples

let v = &mut [0, 0, 0, 0, 0];
let mut count = 1;

for chunk in v.rchunks_exact_mut(2) {
    for elem in chunk.iter_mut() {
        *elem += count;
    }
    count += 1;
}
assert_eq!(v, &[0, 2, 2, 1, 1]);

pub fn chunk_by<F>(&self, pred: F) -> ChunkBy<'_, T, F>

where F: FnMut(&T, &T) -> bool,

Returns an iterator over the slice producing non-overlapping runs of elements using the predicate to separate them.

The predicate is called for every pair of consecutive elements, meaning that it is called on slice[0] and slice[1], followed by slice[1] and slice[2], and so on.

Examples

let slice = &[1, 1, 1, 3, 3, 2, 2, 2];

let mut iter = slice.chunk_by(|a, b| a == b);

assert_eq!(iter.next(), Some(&[1, 1, 1][..]));
assert_eq!(iter.next(), Some(&[3, 3][..]));
assert_eq!(iter.next(), Some(&[2, 2, 2][..]));
assert_eq!(iter.next(), None);

This method can be used to extract the sorted subslices:

let slice = &[1, 1, 2, 3, 2, 3, 2, 3, 4];

let mut iter = slice.chunk_by(|a, b| a <= b);

assert_eq!(iter.next(), Some(&[1, 1, 2, 3][..]));
assert_eq!(iter.next(), Some(&[2, 3][..]));
assert_eq!(iter.next(), Some(&[2, 3, 4][..]));
assert_eq!(iter.next(), None);

pub fn chunk_by_mut<F>(&mut self, pred: F) -> ChunkByMut<'_, T, F>

where F: FnMut(&T, &T) -> bool,

Returns an iterator over the slice producing non-overlapping mutable runs of elements using the predicate to separate them.

The predicate is called for every pair of consecutive elements, meaning that it is called on slice[0] and slice[1], followed by slice[1] and slice[2], and so on.

Examples

let slice = &mut [1, 1, 1, 3, 3, 2, 2, 2];

let mut iter = slice.chunk_by_mut(|a, b| a == b);

assert_eq!(iter.next(), Some(&mut [1, 1, 1][..]));
assert_eq!(iter.next(), Some(&mut [3, 3][..]));
assert_eq!(iter.next(), Some(&mut [2, 2, 2][..]));
assert_eq!(iter.next(), None);

This method can be used to extract the sorted subslices:

let slice = &mut [1, 1, 2, 3, 2, 3, 2, 3, 4];

let mut iter = slice.chunk_by_mut(|a, b| a <= b);

assert_eq!(iter.next(), Some(&mut [1, 1, 2, 3][..]));
assert_eq!(iter.next(), Some(&mut [2, 3][..]));
assert_eq!(iter.next(), Some(&mut [2, 3, 4][..]));
assert_eq!(iter.next(), None);

pub const fn split_at(&self, mid: usize) -> (&[T], &[T])

Divides one slice into two at an index.

The first will contain all indices from [0, mid) (excluding the index mid itself) and the second will contain all indices from [mid, len) (excluding the index len itself).

Panics

Panics if mid > len. For a non-panicking alternative see split_at_checked.

Examples

let v = ['a', 'b', 'c'];

{
   let (left, right) = v.split_at(0);
   assert_eq!(left, []);
   assert_eq!(right, ['a', 'b', 'c']);
}

{
    let (left, right) = v.split_at(2);
    assert_eq!(left, ['a', 'b']);
    assert_eq!(right, ['c']);
}

{
    let (left, right) = v.split_at(3);
    assert_eq!(left, ['a', 'b', 'c']);
    assert_eq!(right, []);
}

pub const fn split_at_mut(&mut self, mid: usize) -> (&mut [T], &mut [T])

Divides one mutable slice into two at an index.

The first will contain all indices from [0, mid) (excluding the index mid itself) and the second will contain all indices from [mid, len) (excluding the index len itself).

Panics

Panics if mid > len. For a non-panicking alternative see split_at_mut_checked.

Examples

let mut v = [1, 0, 3, 0, 5, 6];
let (left, right) = v.split_at_mut(2);
assert_eq!(left, [1, 0]);
assert_eq!(right, [3, 0, 5, 6]);
left[1] = 2;
right[1] = 4;
assert_eq!(v, [1, 2, 3, 4, 5, 6]);

pub const unsafe fn split_at_unchecked(&self, mid: usize) -> (&[T], &[T])

Divides one slice into two at an index, without doing bounds checking.

The first will contain all indices from [0, mid) (excluding the index mid itself) and the second will contain all indices from [mid, len) (excluding the index len itself).

For a safe alternative see split_at.

Safety

Calling this method with an out-of-bounds index is undefined behavior even if the resulting reference is not used. The caller has to ensure that 0 <= mid <= self.len().

Examples

let v = ['a', 'b', 'c'];

unsafe {
   let (left, right) = v.split_at_unchecked(0);
   assert_eq!(left, []);
   assert_eq!(right, ['a', 'b', 'c']);
}

unsafe {
    let (left, right) = v.split_at_unchecked(2);
    assert_eq!(left, ['a', 'b']);
    assert_eq!(right, ['c']);
}

unsafe {
    let (left, right) = v.split_at_unchecked(3);
    assert_eq!(left, ['a', 'b', 'c']);
    assert_eq!(right, []);
}

pub const unsafe fn split_at_mut_unchecked( &mut self, mid: usize, ) -> (&mut [T], &mut [T])

Divides one mutable slice into two at an index, without doing bounds checking.

The first will contain all indices from [0, mid) (excluding the index mid itself) and the second will contain all indices from [mid, len) (excluding the index len itself).

For a safe alternative see split_at_mut.

Safety

Calling this method with an out-of-bounds index is undefined behavior even if the resulting reference is not used. The caller has to ensure that 0 <= mid <= self.len().

Examples

let mut v = [1, 0, 3, 0, 5, 6];
// scoped to restrict the lifetime of the borrows
unsafe {
    let (left, right) = v.split_at_mut_unchecked(2);
    assert_eq!(left, [1, 0]);
    assert_eq!(right, [3, 0, 5, 6]);
    left[1] = 2;
    right[1] = 4;
}
assert_eq!(v, [1, 2, 3, 4, 5, 6]);

pub const fn split_at_checked(&self, mid: usize) -> Option<(&[T], &[T])>

Divides one slice into two at an index, returning None if the slice is too short.

If mid ≤ len returns a pair of slices where the first will contain all indices from [0, mid) (excluding the index mid itself) and the second will contain all indices from [mid, len) (excluding the index len itself).

Otherwise, if mid > len, returns None.

Examples

let v = [1, -2, 3, -4, 5, -6];

{
   let (left, right) = v.split_at_checked(0).unwrap();
   assert_eq!(left, []);
   assert_eq!(right, [1, -2, 3, -4, 5, -6]);
}

{
    let (left, right) = v.split_at_checked(2).unwrap();
    assert_eq!(left, [1, -2]);
    assert_eq!(right, [3, -4, 5, -6]);
}

{
    let (left, right) = v.split_at_checked(6).unwrap();
    assert_eq!(left, [1, -2, 3, -4, 5, -6]);
    assert_eq!(right, []);
}

assert_eq!(None, v.split_at_checked(7));

pub const fn split_at_mut_checked( &mut self, mid: usize, ) -> Option<(&mut [T], &mut [T])>

Divides one mutable slice into two at an index, returning None if the slice is too short.

If mid ≤ len returns a pair of slices where the first will contain all indices from [0, mid) (excluding the index mid itself) and the second will contain all indices from [mid, len) (excluding the index len itself).

Otherwise, if mid > len, returns None.

Examples

let mut v = [1, 0, 3, 0, 5, 6];

if let Some((left, right)) = v.split_at_mut_checked(2) {
    assert_eq!(left, [1, 0]);
    assert_eq!(right, [3, 0, 5, 6]);
    left[1] = 2;
    right[1] = 4;
}
assert_eq!(v, [1, 2, 3, 4, 5, 6]);

assert_eq!(None, v.split_at_mut_checked(7));

pub fn split<F>(&self, pred: F) -> Split<'_, T, F>

where F: FnMut(&T) -> bool,

Returns an iterator over subslices separated by elements that match pred. The matched element is not contained in the subslices.

Examples

let slice = [10, 40, 33, 20];
let mut iter = slice.split(|num| num % 3 == 0);

assert_eq!(iter.next().unwrap(), &[10, 40]);
assert_eq!(iter.next().unwrap(), &[20]);
assert!(iter.next().is_none());

If the first element is matched, an empty slice will be the first item returned by the iterator. Similarly, if the last element in the slice is matched, an empty slice will be the last item returned by the iterator:

let slice = [10, 40, 33];
let mut iter = slice.split(|num| num % 3 == 0);

assert_eq!(iter.next().unwrap(), &[10, 40]);
assert_eq!(iter.next().unwrap(), &[]);
assert!(iter.next().is_none());

If two matched elements are directly adjacent, an empty slice will be present between them:

let slice = [10, 6, 33, 20];
let mut iter = slice.split(|num| num % 3 == 0);

assert_eq!(iter.next().unwrap(), &[10]);
assert_eq!(iter.next().unwrap(), &[]);
assert_eq!(iter.next().unwrap(), &[20]);
assert!(iter.next().is_none());

pub fn split_mut<F>(&mut self, pred: F) -> SplitMut<'_, T, F>

where F: FnMut(&T) -> bool,

Returns an iterator over mutable subslices separated by elements that match pred. The matched element is not contained in the subslices.

Examples

let mut v = [10, 40, 30, 20, 60, 50];

for group in v.split_mut(|num| *num % 3 == 0) {
    group[0] = 1;
}
assert_eq!(v, [1, 40, 30, 1, 60, 1]);

pub fn split_inclusive<F>(&self, pred: F) -> SplitInclusive<'_, T, F>

where F: FnMut(&T) -> bool,

Returns an iterator over subslices separated by elements that match pred. The matched element is contained in the end of the previous subslice as a terminator.

Examples

let slice = [10, 40, 33, 20];
let mut iter = slice.split_inclusive(|num| num % 3 == 0);

assert_eq!(iter.next().unwrap(), &[10, 40, 33]);
assert_eq!(iter.next().unwrap(), &[20]);
assert!(iter.next().is_none());

If the last element of the slice is matched, that element will be considered the terminator of the preceding slice. That slice will be the last item returned by the iterator.

let slice = [3, 10, 40, 33];
let mut iter = slice.split_inclusive(|num| num % 3 == 0);

assert_eq!(iter.next().unwrap(), &[3]);
assert_eq!(iter.next().unwrap(), &[10, 40, 33]);
assert!(iter.next().is_none());

pub fn split_inclusive_mut<F>(&mut self, pred: F) -> SplitInclusiveMut<'_, T, F>

where F: FnMut(&T) -> bool,

Returns an iterator over mutable subslices separated by elements that match pred. The matched element is contained in the previous subslice as a terminator.

Examples

let mut v = [10, 40, 30, 20, 60, 50];

for group in v.split_inclusive_mut(|num| *num % 3 == 0) {
    let terminator_idx = group.len()-1;
    group[terminator_idx] = 1;
}
assert_eq!(v, [10, 40, 1, 20, 1, 1]);

pub fn rsplit<F>(&self, pred: F) -> RSplit<'_, T, F>

where F: FnMut(&T) -> bool,

Returns an iterator over subslices separated by elements that match pred, starting at the end of the slice and working backwards. The matched element is not contained in the subslices.

Examples

let slice = [11, 22, 33, 0, 44, 55];
let mut iter = slice.rsplit(|num| *num == 0);

assert_eq!(iter.next().unwrap(), &[44, 55]);
assert_eq!(iter.next().unwrap(), &[11, 22, 33]);
assert_eq!(iter.next(), None);

As with split(), if the first or last element is matched, an empty slice will be the first (or last) item returned by the iterator.

let v = &[0, 1, 1, 2, 3, 5, 8];
let mut it = v.rsplit(|n| *n % 2 == 0);
assert_eq!(it.next().unwrap(), &[]);
assert_eq!(it.next().unwrap(), &[3, 5]);
assert_eq!(it.next().unwrap(), &[1, 1]);
assert_eq!(it.next().unwrap(), &[]);
assert_eq!(it.next(), None);

pub fn rsplit_mut<F>(&mut self, pred: F) -> RSplitMut<'_, T, F>

where F: FnMut(&T) -> bool,

Returns an iterator over mutable subslices separated by elements that match pred, starting at the end of the slice and working backwards. The matched element is not contained in the subslices.

Examples

let mut v = [100, 400, 300, 200, 600, 500];

let mut count = 0;
for group in v.rsplit_mut(|num| *num % 3 == 0) {
    count += 1;
    group[0] = count;
}
assert_eq!(v, [3, 400, 300, 2, 600, 1]);

pub fn splitn<F>(&self, n: usize, pred: F) -> SplitN<'_, T, F>

where F: FnMut(&T) -> bool,

Returns an iterator over subslices separated by elements that match pred, limited to returning at most n items. The matched element is not contained in the subslices.

The last element returned, if any, will contain the remainder of the slice.

Examples

Print the slice split once by numbers divisible by 3 (i.e., [10, 40], [20, 60, 50]):

let v = [10, 40, 30, 20, 60, 50];

for group in v.splitn(2, |num| *num % 3 == 0) {
    println!("{group:?}");
}

pub fn splitn_mut<F>(&mut self, n: usize, pred: F) -> SplitNMut<'_, T, F>

where F: FnMut(&T) -> bool,

Returns an iterator over mutable subslices separated by elements that match pred, limited to returning at most n items. The matched element is not contained in the subslices.

The last element returned, if any, will contain the remainder of the slice.

Examples

let mut v = [10, 40, 30, 20, 60, 50];

for group in v.splitn_mut(2, |num| *num % 3 == 0) {
    group[0] = 1;
}
assert_eq!(v, [1, 40, 30, 1, 60, 50]);

pub fn rsplitn<F>(&self, n: usize, pred: F) -> RSplitN<'_, T, F>

where F: FnMut(&T) -> bool,

Returns an iterator over subslices separated by elements that match pred limited to returning at most n items. This starts at the end of the slice and works backwards. The matched element is not contained in the subslices.

The last element returned, if any, will contain the remainder of the slice.

Examples

Print the slice split once, starting from the end, by numbers divisible by 3 (i.e., [50], [10, 40, 30, 20]):

let v = [10, 40, 30, 20, 60, 50];

for group in v.rsplitn(2, |num| *num % 3 == 0) {
    println!("{group:?}");
}

pub fn rsplitn_mut<F>(&mut self, n: usize, pred: F) -> RSplitNMut<'_, T, F>

where F: FnMut(&T) -> bool,

Returns an iterator over subslices separated by elements that match pred limited to returning at most n items. This starts at the end of the slice and works backwards. The matched element is not contained in the subslices.

The last element returned, if any, will contain the remainder of the slice.

Examples

let mut s = [10, 40, 30, 20, 60, 50];

for group in s.rsplitn_mut(2, |num| *num % 3 == 0) {
    group[0] = 1;
}
assert_eq!(s, [1, 40, 30, 20, 60, 1]);

pub fn split_once<F>(&self, pred: F) -> Option<(&[T], &[T])>

where F: FnMut(&T) -> bool,

🔬This is a nightly-only experimental API. (slice_split_once #112811)

Splits the slice on the first element that matches the specified predicate.

If any matching elements are present in the slice, returns the prefix before the match and suffix after. The matching element itself is not included. If no elements match, returns None.

Examples

#![feature(slice_split_once)]
let s = [1, 2, 3, 2, 4];
assert_eq!(s.split_once(|&x| x == 2), Some((
    &[1][..],
    &[3, 2, 4][..]
)));
assert_eq!(s.split_once(|&x| x == 0), None);

pub fn rsplit_once<F>(&self, pred: F) -> Option<(&[T], &[T])>

where F: FnMut(&T) -> bool,

🔬This is a nightly-only experimental API. (slice_split_once #112811)

Splits the slice on the last element that matches the specified predicate.

If any matching elements are present in the slice, returns the prefix before the match and suffix after. The matching element itself is not included. If no elements match, returns None.

Examples

#![feature(slice_split_once)]
let s = [1, 2, 3, 2, 4];
assert_eq!(s.rsplit_once(|&x| x == 2), Some((
    &[1, 2, 3][..],
    &[4][..]
)));
assert_eq!(s.rsplit_once(|&x| x == 0), None);

pub fn contains(&self, x: &T) -> bool

where T: PartialEq,

Returns true if the slice contains an element with the given value.

This operation is O(n).

Note that if you have a sorted slice, binary_search may be faster.

Examples

let v = [10, 40, 30];
assert!(v.contains(&30));
assert!(!v.contains(&50));

If you do not have a &T, but some other value that you can compare with one (for example, String implements PartialEq<str>), you can use iter().any:

let v = [String::from("hello"), String::from("world")]; // slice of `String`
assert!(v.iter().any(|e| e == "hello")); // search with `&str`
assert!(!v.iter().any(|e| e == "hi"));

pub fn starts_with(&self, needle: &[T]) -> bool

where T: PartialEq,

Returns true if needle is a prefix of the slice or equal to the slice.

Examples

let v = [10, 40, 30];
assert!(v.starts_with(&[10]));
assert!(v.starts_with(&[10, 40]));
assert!(v.starts_with(&v));
assert!(!v.starts_with(&[50]));
assert!(!v.starts_with(&[10, 50]));

Always returns true if needle is an empty slice:

let v = &[10, 40, 30];
assert!(v.starts_with(&[]));
let v: &[u8] = &[];
assert!(v.starts_with(&[]));

pub fn ends_with(&self, needle: &[T]) -> bool

where T: PartialEq,

Returns true if needle is a suffix of the slice or equal to the slice.

Examples

let v = [10, 40, 30];
assert!(v.ends_with(&[30]));
assert!(v.ends_with(&[40, 30]));
assert!(v.ends_with(&v));
assert!(!v.ends_with(&[50]));
assert!(!v.ends_with(&[50, 30]));

Always returns true if needle is an empty slice:

let v = &[10, 40, 30];
assert!(v.ends_with(&[]));
let v: &[u8] = &[];
assert!(v.ends_with(&[]));

pub fn strip_prefix<P>(&self, prefix: &P) -> Option<&[T]>

where P: SlicePattern<Item = T> + ?Sized, T: PartialEq,

Returns a subslice with the prefix removed.

If the slice starts with prefix, returns the subslice after the prefix, wrapped in Some. If prefix is empty, simply returns the original slice. If prefix is equal to the original slice, returns an empty slice.

If the slice does not start with prefix, returns None.

Examples

let v = &[10, 40, 30];
assert_eq!(v.strip_prefix(&[10]), Some(&[40, 30][..]));
assert_eq!(v.strip_prefix(&[10, 40]), Some(&[30][..]));
assert_eq!(v.strip_prefix(&[10, 40, 30]), Some(&[][..]));
assert_eq!(v.strip_prefix(&[50]), None);
assert_eq!(v.strip_prefix(&[10, 50]), None);

let prefix : &str = "he";
assert_eq!(b"hello".strip_prefix(prefix.as_bytes()),
           Some(b"llo".as_ref()));

pub fn strip_suffix<P>(&self, suffix: &P) -> Option<&[T]>

where P: SlicePattern<Item = T> + ?Sized, T: PartialEq,

Returns a subslice with the suffix removed.

If the slice ends with suffix, returns the subslice before the suffix, wrapped in Some. If suffix is empty, simply returns the original slice. If suffix is equal to the original slice, returns an empty slice.

If the slice does not end with suffix, returns None.

Examples

let v = &[10, 40, 30];
assert_eq!(v.strip_suffix(&[30]), Some(&[10, 40][..]));
assert_eq!(v.strip_suffix(&[40, 30]), Some(&[10][..]));
assert_eq!(v.strip_suffix(&[10, 40, 30]), Some(&[][..]));
assert_eq!(v.strip_suffix(&[50]), None);
assert_eq!(v.strip_suffix(&[50, 30]), None);

pub fn binary_search(&self, x: &T) -> Result<usize, usize>

where T: Ord,

Binary searches this slice for a given element. If the slice is not sorted, the returned result is unspecified and meaningless.

If the value is found then Result::Ok is returned, containing the index of the matching element. If there are multiple matches, then any one of the matches could be returned. The index is chosen deterministically, but is subject to change in future versions of Rust. If the value is not found then Result::Err is returned, containing the index where a matching element could be inserted while maintaining sorted order.

See also binary_search_by, binary_search_by_key, and partition_point.

Examples

Looks up a series of four elements. The first is found, with a uniquely determined position; the second and third are not found; the fourth could match any position in [1, 4].

let s = [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];

assert_eq!(s.binary_search(&13),  Ok(9));
assert_eq!(s.binary_search(&4),   Err(7));
assert_eq!(s.binary_search(&100), Err(13));
let r = s.binary_search(&1);
assert!(match r { Ok(1..=4) => true, _ => false, });

If you want to find that whole range of matching items, rather than an arbitrary matching one, that can be done using partition_point:

let s = [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];

let low = s.partition_point(|x| x < &1);
assert_eq!(low, 1);
let high = s.partition_point(|x| x <= &1);
assert_eq!(high, 5);
let r = s.binary_search(&1);
assert!((low..high).contains(&r.unwrap()));

assert!(s[..low].iter().all(|&x| x < 1));
assert!(s[low..high].iter().all(|&x| x == 1));
assert!(s[high..].iter().all(|&x| x > 1));

// For something not found, the "range" of equal items is empty
assert_eq!(s.partition_point(|x| x < &11), 9);
assert_eq!(s.partition_point(|x| x <= &11), 9);
assert_eq!(s.binary_search(&11), Err(9));

If you want to insert an item to a sorted vector, while maintaining sort order, consider using partition_point:

let mut s = vec![0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];
let num = 42;
let idx = s.partition_point(|&x| x <= num);
// If `num` is unique, `s.partition_point(|&x| x < num)` (with `<`) is equivalent to
// `s.binary_search(&num).unwrap_or_else(|x| x)`, but using `<=` will allow `insert`
// to shift less elements.
s.insert(idx, num);
assert_eq!(s, [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 42, 55]);

pub fn binary_search_by<'a, F>(&'a self, f: F) -> Result<usize, usize>

where F: FnMut(&'a T) -> Ordering,

Binary searches this slice with a comparator function.

The comparator function should return an order code that indicates whether its argument is Less, Equal or Greater the desired target. If the slice is not sorted or if the comparator function does not implement an order consistent with the sort order of the underlying slice, the returned result is unspecified and meaningless.

If the value is found then Result::Ok is returned, containing the index of the matching element. If there are multiple matches, then any one of the matches could be returned. The index is chosen deterministically, but is subject to change in future versions of Rust. If the value is not found then Result::Err is returned, containing the index where a matching element could be inserted while maintaining sorted order.

See also binary_search, binary_search_by_key, and partition_point.

Examples

Looks up a series of four elements. The first is found, with a uniquely determined position; the second and third are not found; the fourth could match any position in [1, 4].

let s = [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];

let seek = 13;
assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Ok(9));
let seek = 4;
assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Err(7));
let seek = 100;
assert_eq!(s.binary_search_by(|probe| probe.cmp(&seek)), Err(13));
let seek = 1;
let r = s.binary_search_by(|probe| probe.cmp(&seek));
assert!(match r { Ok(1..=4) => true, _ => false, });

pub fn binary_search_by_key<'a, B, F>( &'a self, b: &B, f: F, ) -> Result<usize, usize>

where F: FnMut(&'a T) -> B, B: Ord,

Binary searches this slice with a key extraction function.

Assumes that the slice is sorted by the key, for instance with sort_by_key using the same key extraction function. If the slice is not sorted by the key, the returned result is unspecified and meaningless.

If the value is found then Result::Ok is returned, containing the index of the matching element. If there are multiple matches, then any one of the matches could be returned. The index is chosen deterministically, but is subject to change in future versions of Rust. If the value is not found then Result::Err is returned, containing the index where a matching element could be inserted while maintaining sorted order.

See also binary_search, binary_search_by, and partition_point.

Examples

Looks up a series of four elements in a slice of pairs sorted by their second elements. The first is found, with a uniquely determined position; the second and third are not found; the fourth could match any position in [1, 4].

let s = [(0, 0), (2, 1), (4, 1), (5, 1), (3, 1),
         (1, 2), (2, 3), (4, 5), (5, 8), (3, 13),
         (1, 21), (2, 34), (4, 55)];

assert_eq!(s.binary_search_by_key(&13, |&(a, b)| b),  Ok(9));
assert_eq!(s.binary_search_by_key(&4, |&(a, b)| b),   Err(7));
assert_eq!(s.binary_search_by_key(&100, |&(a, b)| b), Err(13));
let r = s.binary_search_by_key(&1, |&(a, b)| b);
assert!(match r { Ok(1..=4) => true, _ => false, });

pub fn sort_unstable(&mut self)

where T: Ord,

Sorts the slice without preserving the initial order of equal elements.

This sort is unstable (i.e., may reorder equal elements), in-place (i.e., does not allocate), and O(n * log(n)) worst-case.

If the implementation of Ord for T does not implement a total order the resulting order of elements in the slice is unspecified. All original elements will remain in the slice and any possible modifications via interior mutability are observed in the input. Same is true if the implementation of Ord for T panics.

Sorting types that only implement PartialOrd such as f32 and f64 require additional precautions. For example, f32::NAN != f32::NAN, which doesn’t fulfill the reflexivity requirement of Ord. By using an alternative comparison function with slice::sort_unstable_by such as f32::total_cmp or f64::total_cmp that defines a total order users can sort slices containing floating-point values. Alternatively, if all values in the slice are guaranteed to be in a subset for which PartialOrd::partial_cmp forms a total order, it’s possible to sort the slice with sort_unstable_by(|a, b| a.partial_cmp(b).unwrap()).

Current implementation

The current implementation is based on ipnsort by Lukas Bergdoll and Orson Peters, which combines the fast average case of quicksort with the fast worst case of heapsort, achieving linear time on fully sorted and reversed inputs. On inputs with k distinct elements, the expected time to sort the data is O(n * log(k)).

It is typically faster than stable sorting, except in a few special cases, e.g., when the slice is partially sorted.

Panics

May panic if the implementation of Ord for T does not implement a total order.

Examples

let mut v = [4, -5, 1, -3, 2];

v.sort_unstable();
assert_eq!(v, [-5, -3, 1, 2, 4]);

pub fn sort_unstable_by<F>(&mut self, compare: F)

where F: FnMut(&T, &T) -> Ordering,

Sorts the slice with a comparison function, without preserving the initial order of equal elements.

This sort is unstable (i.e., may reorder equal elements), in-place (i.e., does not allocate), and O(n * log(n)) worst-case.

If the comparison function compare does not implement a total order the resulting order of elements in the slice is unspecified. All original elements will remain in the slice and any possible modifications via interior mutability are observed in the input. Same is true if compare panics.

For example |a, b| (a - b).cmp(a) is a comparison function that is neither transitive nor reflexive nor total, a < b < c < a with a = 1, b = 2, c = 3. For more information and examples see the Ord documentation.

Current implementation

The current implementation is based on ipnsort by Lukas Bergdoll and Orson Peters, which combines the fast average case of quicksort with the fast worst case of heapsort, achieving linear time on fully sorted and reversed inputs. On inputs with k distinct elements, the expected time to sort the data is O(n * log(k)).

It is typically faster than stable sorting, except in a few special cases, e.g., when the slice is partially sorted.

Panics

May panic if compare does not implement a total order.

Examples

let mut v = [4, -5, 1, -3, 2];
v.sort_unstable_by(|a, b| a.cmp(b));
assert_eq!(v, [-5, -3, 1, 2, 4]);

// reverse sorting
v.sort_unstable_by(|a, b| b.cmp(a));
assert_eq!(v, [4, 2, 1, -3, -5]);

pub fn sort_unstable_by_key<K, F>(&mut self, f: F)

where F: FnMut(&T) -> K, K: Ord,

Sorts the slice with a key extraction function, without preserving the initial order of equal elements.

This sort is unstable (i.e., may reorder equal elements), in-place (i.e., does not allocate), and O(n * log(n)) worst-case.

If the implementation of Ord for K does not implement a total order the resulting order of elements in the slice is unspecified. All original elements will remain in the slice and any possible modifications via interior mutability are observed in the input. Same is true if the implementation of Ord for K panics.

Current implementation

The current implementation is based on ipnsort by Lukas Bergdoll and Orson Peters, which combines the fast average case of quicksort with the fast worst case of heapsort, achieving linear time on fully sorted and reversed inputs. On inputs with k distinct elements, the expected time to sort the data is O(n * log(k)).

It is typically faster than stable sorting, except in a few special cases, e.g., when the slice is partially sorted.

Panics

May panic if the implementation of Ord for K does not implement a total order.

Examples

let mut v = [4i32, -5, 1, -3, 2];

v.sort_unstable_by_key(|k| k.abs());
assert_eq!(v, [1, 2, -3, 4, -5]);

pub fn select_nth_unstable( &mut self, index: usize, ) -> (&mut [T], &mut T, &mut [T])

where T: Ord,

Reorders the slice such that the element at index after the reordering is at its final sorted position.

This reordering has the additional property that any value at position i < index will be less than or equal to any value at a position j > index. Additionally, this reordering is unstable (i.e. any number of equal elements may end up at position index), in-place (i.e. does not allocate), and runs in O(n) time. This function is also known as “kth element” in other libraries.

It returns a triplet of the following from the reordered slice: the subslice prior to index, the element at index, and the subslice after index; accordingly, the values in those two subslices will respectively all be less-than-or-equal-to and greater-than-or-equal-to the value of the element at index.

Current implementation

The current algorithm is an introselect implementation based on ipnsort by Lukas Bergdoll and Orson Peters, which is also the basis for sort_unstable. The fallback algorithm is Median of Medians using Tukey’s Ninther for pivot selection, which guarantees linear runtime for all inputs.

Panics

Panics when index >= len(), meaning it always panics on empty slices.

May panic if the implementation of Ord for T does not implement a total order.

Examples

let mut v = [-5i32, 4, 2, -3, 1];

// Find the items less than or equal to the median, the median, and greater than or equal to
// the median.
let (lesser, median, greater) = v.select_nth_unstable(2);

assert!(lesser == [-3, -5] || lesser == [-5, -3]);
assert_eq!(median, &mut 1);
assert!(greater == [4, 2] || greater == [2, 4]);

// We are only guaranteed the slice will be one of the following, based on the way we sort
// about the specified index.
assert!(v == [-3, -5, 1, 2, 4] ||
        v == [-5, -3, 1, 2, 4] ||
        v == [-3, -5, 1, 4, 2] ||
        v == [-5, -3, 1, 4, 2]);

pub fn select_nth_unstable_by<F>( &mut self, index: usize, compare: F, ) -> (&mut [T], &mut T, &mut [T])

where F: FnMut(&T, &T) -> Ordering,

Reorders the slice with a comparator function such that the element at index after the reordering is at its final sorted position.

This reordering has the additional property that any value at position i < index will be less than or equal to any value at a position j > index using the comparator function. Additionally, this reordering is unstable (i.e. any number of equal elements may end up at position index), in-place (i.e. does not allocate), and runs in O(n) time. This function is also known as “kth element” in other libraries.

It returns a triplet of the following from the slice reordered according to the provided comparator function: the subslice prior to index, the element at index, and the subslice after index; accordingly, the values in those two subslices will respectively all be less-than-or-equal-to and greater-than-or-equal-to the value of the element at index.

Current implementation

The current algorithm is an introselect implementation based on ipnsort by Lukas Bergdoll and Orson Peters, which is also the basis for sort_unstable. The fallback algorithm is Median of Medians using Tukey’s Ninther for pivot selection, which guarantees linear runtime for all inputs.

Panics

Panics when index >= len(), meaning it always panics on empty slices.

May panic if compare does not implement a total order.

Examples

let mut v = [-5i32, 4, 2, -3, 1];

// Find the items less than or equal to the median, the median, and greater than or equal to
// the median as if the slice were sorted in descending order.
let (lesser, median, greater) = v.select_nth_unstable_by(2, |a, b| b.cmp(a));

assert!(lesser == [4, 2] || lesser == [2, 4]);
assert_eq!(median, &mut 1);
assert!(greater == [-3, -5] || greater == [-5, -3]);

// We are only guaranteed the slice will be one of the following, based on the way we sort
// about the specified index.
assert!(v == [2, 4, 1, -5, -3] ||
        v == [2, 4, 1, -3, -5] ||
        v == [4, 2, 1, -5, -3] ||
        v == [4, 2, 1, -3, -5]);

pub fn select_nth_unstable_by_key<K, F>( &mut self, index: usize, f: F, ) -> (&mut [T], &mut T, &mut [T])

where F: FnMut(&T) -> K, K: Ord,

Reorders the slice with a key extraction function such that the element at index after the reordering is at its final sorted position.

This reordering has the additional property that any value at position i < index will be less than or equal to any value at a position j > index using the key extraction function. Additionally, this reordering is unstable (i.e. any number of equal elements may end up at position index), in-place (i.e. does not allocate), and runs in O(n) time. This function is also known as “kth element” in other libraries.

It returns a triplet of the following from the slice reordered according to the provided key extraction function: the subslice prior to index, the element at index, and the subslice after index; accordingly, the values in those two subslices will respectively all be less-than-or-equal-to and greater-than-or-equal-to the value of the element at index.

Current implementation

The current algorithm is an introselect implementation based on ipnsort by Lukas Bergdoll and Orson Peters, which is also the basis for sort_unstable. The fallback algorithm is Median of Medians using Tukey’s Ninther for pivot selection, which guarantees linear runtime for all inputs.

Panics

Panics when index >= len(), meaning it always panics on empty slices.

May panic if K: Ord does not implement a total order.

Examples

let mut v = [-5i32, 4, 1, -3, 2];

// Find the items less than or equal to the median, the median, and greater than or equal to
// the median as if the slice were sorted according to absolute value.
let (lesser, median, greater) = v.select_nth_unstable_by_key(2, |a| a.abs());

assert!(lesser == [1, 2] || lesser == [2, 1]);
assert_eq!(median, &mut -3);
assert!(greater == [4, -5] || greater == [-5, 4]);

// We are only guaranteed the slice will be one of the following, based on the way we sort
// about the specified index.
assert!(v == [1, 2, -3, 4, -5] ||
        v == [1, 2, -3, -5, 4] ||
        v == [2, 1, -3, 4, -5] ||
        v == [2, 1, -3, -5, 4]);

pub fn partition_dedup(&mut self) -> (&mut [T], &mut [T])

where T: PartialEq,

🔬This is a nightly-only experimental API. (slice_partition_dedup #54279)

Moves all consecutive repeated elements to the end of the slice according to the PartialEq trait implementation.

Returns two slices. The first contains no consecutive repeated elements. The second contains all the duplicates in no specified order.

If the slice is sorted, the first returned slice contains no duplicates.

Examples

#![feature(slice_partition_dedup)]

let mut slice = [1, 2, 2, 3, 3, 2, 1, 1];

let (dedup, duplicates) = slice.partition_dedup();

assert_eq!(dedup, [1, 2, 3, 2, 1]);
assert_eq!(duplicates, [2, 3, 1]);

pub fn partition_dedup_by<F>(&mut self, same_bucket: F) -> (&mut [T], &mut [T])

where F: FnMut(&mut T, &mut T) -> bool,

🔬This is a nightly-only experimental API. (slice_partition_dedup #54279)

Moves all but the first of consecutive elements to the end of the slice satisfying a given equality relation.

Returns two slices. The first contains no consecutive repeated elements. The second contains all the duplicates in no specified order.

The same_bucket function is passed references to two elements from the slice and must determine if the elements compare equal. The elements are passed in opposite order from their order in the slice, so if same_bucket(a, b) returns true, a is moved at the end of the slice.

If the slice is sorted, the first returned slice contains no duplicates.

Examples

#![feature(slice_partition_dedup)]

let mut slice = ["foo", "Foo", "BAZ", "Bar", "bar", "baz", "BAZ"];

let (dedup, duplicates) = slice.partition_dedup_by(|a, b| a.eq_ignore_ascii_case(b));

assert_eq!(dedup, ["foo", "BAZ", "Bar", "baz"]);
assert_eq!(duplicates, ["bar", "Foo", "BAZ"]);

pub fn partition_dedup_by_key<K, F>(&mut self, key: F) -> (&mut [T], &mut [T])

where F: FnMut(&mut T) -> K, K: PartialEq,

🔬This is a nightly-only experimental API. (slice_partition_dedup #54279)

Moves all but the first of consecutive elements to the end of the slice that resolve to the same key.

Returns two slices. The first contains no consecutive repeated elements. The second contains all the duplicates in no specified order.

If the slice is sorted, the first returned slice contains no duplicates.

Examples

#![feature(slice_partition_dedup)]

let mut slice = [10, 20, 21, 30, 30, 20, 11, 13];

let (dedup, duplicates) = slice.partition_dedup_by_key(|i| *i / 10);

assert_eq!(dedup, [10, 20, 30, 20, 11]);
assert_eq!(duplicates, [21, 30, 13]);

pub fn rotate_left(&mut self, mid: usize)

Rotates the slice in-place such that the first mid elements of the slice move to the end while the last self.len() - mid elements move to the front.

After calling rotate_left, the element previously at index mid will become the first element in the slice.

Panics

This function will panic if mid is greater than the length of the slice. Note that mid == self.len() does not panic and is a no-op rotation.

Complexity

Takes linear (in self.len()) time.

Examples

let mut a = ['a', 'b', 'c', 'd', 'e', 'f'];
a.rotate_left(2);
assert_eq!(a, ['c', 'd', 'e', 'f', 'a', 'b']);

Rotating a subslice:

let mut a = ['a', 'b', 'c', 'd', 'e', 'f'];
a[1..5].rotate_left(1);
assert_eq!(a, ['a', 'c', 'd', 'e', 'b', 'f']);

pub fn rotate_right(&mut self, k: usize)

Rotates the slice in-place such that the first self.len() - k elements of the slice move to the end while the last k elements move to the front.

After calling rotate_right, the element previously at index self.len() - k will become the first element in the slice.

Panics

This function will panic if k is greater than the length of the slice. Note that k == self.len() does not panic and is a no-op rotation.

Complexity

Takes linear (in self.len()) time.

Examples

let mut a = ['a', 'b', 'c', 'd', 'e', 'f'];
a.rotate_right(2);
assert_eq!(a, ['e', 'f', 'a', 'b', 'c', 'd']);

Rotating a subslice:

let mut a = ['a', 'b', 'c', 'd', 'e', 'f'];
a[1..5].rotate_right(1);
assert_eq!(a, ['a', 'e', 'b', 'c', 'd', 'f']);

pub fn fill(&mut self, value: T)

where T: Clone,

Fills self with elements by cloning value.

Examples

let mut buf = vec![0; 10];
buf.fill(1);
assert_eq!(buf, vec![1; 10]);

pub fn fill_with<F>(&mut self, f: F)

where F: FnMut() -> T,

Fills self with elements returned by calling a closure repeatedly.

This method uses a closure to create new values. If you’d rather Clone a given value, use fill. If you want to use the Default trait to generate values, you can pass Default::default as the argument.

Examples

let mut buf = vec![1; 10];
buf.fill_with(Default::default);
assert_eq!(buf, vec![0; 10]);

pub fn clone_from_slice(&mut self, src: &[T])

where T: Clone,

Copies the elements from src into self.

The length of src must be the same as self.

Panics

This function will panic if the two slices have different lengths.

Examples

Cloning two elements from a slice into another:

let src = [1, 2, 3, 4];
let mut dst = [0, 0];

// Because the slices have to be the same length,
// we slice the source slice from four elements
// to two. It will panic if we don't do this.
dst.clone_from_slice(&src[2..]);

assert_eq!(src, [1, 2, 3, 4]);
assert_eq!(dst, [3, 4]);

Rust enforces that there can only be one mutable reference with no immutable references to a particular piece of data in a particular scope. Because of this, attempting to use clone_from_slice on a single slice will result in a compile failure:

let mut slice = [1, 2, 3, 4, 5];

slice[..2].clone_from_slice(&slice[3..]); // compile fail!

To work around this, we can use split_at_mut to create two distinct sub-slices from a slice:

let mut slice = [1, 2, 3, 4, 5];

{
    let (left, right) = slice.split_at_mut(2);
    left.clone_from_slice(&right[1..]);
}

assert_eq!(slice, [4, 5, 3, 4, 5]);

pub fn copy_from_slice(&mut self, src: &[T])

where T: Copy,

Copies all elements from src into self, using a memcpy.

The length of src must be the same as self.

If T does not implement Copy, use clone_from_slice.

Panics

This function will panic if the two slices have different lengths.

Examples

Copying two elements from a slice into another:

let src = [1, 2, 3, 4];
let mut dst = [0, 0];

// Because the slices have to be the same length,
// we slice the source slice from four elements
// to two. It will panic if we don't do this.
dst.copy_from_slice(&src[2..]);

assert_eq!(src, [1, 2, 3, 4]);
assert_eq!(dst, [3, 4]);

Rust enforces that there can only be one mutable reference with no immutable references to a particular piece of data in a particular scope. Because of this, attempting to use copy_from_slice on a single slice will result in a compile failure:

let mut slice = [1, 2, 3, 4, 5];

slice[..2].copy_from_slice(&slice[3..]); // compile fail!

To work around this, we can use split_at_mut to create two distinct sub-slices from a slice:

let mut slice = [1, 2, 3, 4, 5];

{
    let (left, right) = slice.split_at_mut(2);
    left.copy_from_slice(&right[1..]);
}

assert_eq!(slice, [4, 5, 3, 4, 5]);

pub fn copy_within<R>(&mut self, src: R, dest: usize)

where R: RangeBounds<usize>, T: Copy,

Copies elements from one part of the slice to another part of itself, using a memmove.

src is the range within self to copy from. dest is the starting index of the range within self to copy to, which will have the same length as src. The two ranges may overlap. The ends of the two ranges must be less than or equal to self.len().

Panics

This function will panic if either range exceeds the end of the slice, or if the end of src is before the start.

Examples

Copying four bytes within a slice:

let mut bytes = *b"Hello, World!";

bytes.copy_within(1..5, 8);

assert_eq!(&bytes, b"Hello, Wello!");

pub fn swap_with_slice(&mut self, other: &mut [T])

Swaps all elements in self with those in other.

The length of other must be the same as self.

Panics

This function will panic if the two slices have different lengths.

Example

Swapping two elements across slices:

let mut slice1 = [0, 0];
let mut slice2 = [1, 2, 3, 4];

slice1.swap_with_slice(&mut slice2[2..]);

assert_eq!(slice1, [3, 4]);
assert_eq!(slice2, [1, 2, 0, 0]);

Rust enforces that there can only be one mutable reference to a particular piece of data in a particular scope. Because of this, attempting to use swap_with_slice on a single slice will result in a compile failure:

let mut slice = [1, 2, 3, 4, 5];
slice[..2].swap_with_slice(&mut slice[3..]); // compile fail!

To work around this, we can use split_at_mut to create two distinct mutable sub-slices from a slice:

let mut slice = [1, 2, 3, 4, 5];

{
    let (left, right) = slice.split_at_mut(2);
    left.swap_with_slice(&mut right[1..]);
}

assert_eq!(slice, [4, 5, 3, 1, 2]);

pub unsafe fn align_to<U>(&self) -> (&[T], &[U], &[T])

Transmutes the slice to a slice of another type, ensuring alignment of the types is maintained.

This method splits the slice into three distinct slices: prefix, correctly aligned middle slice of a new type, and the suffix slice. The middle part will be as big as possible under the given alignment constraint and element size.

This method has no purpose when either input element T or output element U are zero-sized and will return the original slice without splitting anything.

Safety

This method is essentially a transmute with respect to the elements in the returned middle slice, so all the usual caveats pertaining to transmute::<T, U> also apply here.

Examples

Basic usage:

unsafe {
    let bytes: [u8; 7] = [1, 2, 3, 4, 5, 6, 7];
    let (prefix, shorts, suffix) = bytes.align_to::<u16>();
    // less_efficient_algorithm_for_bytes(prefix);
    // more_efficient_algorithm_for_aligned_shorts(shorts);
    // less_efficient_algorithm_for_bytes(suffix);
}

pub unsafe fn align_to_mut<U>(&mut self) -> (&mut [T], &mut [U], &mut [T])

Transmutes the mutable slice to a mutable slice of another type, ensuring alignment of the types is maintained.

This method splits the slice into three distinct slices: prefix, correctly aligned middle slice of a new type, and the suffix slice. The middle part will be as big as possible under the given alignment constraint and element size.

This method has no purpose when either input element T or output element U are zero-sized and will return the original slice without splitting anything.

Safety

This method is essentially a transmute with respect to the elements in the returned middle slice, so all the usual caveats pertaining to transmute::<T, U> also apply here.

Examples

Basic usage:

unsafe {
    let mut bytes: [u8; 7] = [1, 2, 3, 4, 5, 6, 7];
    let (prefix, shorts, suffix) = bytes.align_to_mut::<u16>();
    // less_efficient_algorithm_for_bytes(prefix);
    // more_efficient_algorithm_for_aligned_shorts(shorts);
    // less_efficient_algorithm_for_bytes(suffix);
}

pub fn as_simd<const LANES: usize>(&self) -> (&[T], &[Simd<T, LANES>], &[T])

where Simd<T, LANES>: AsRef<[T; LANES]>, T: SimdElement, LaneCount<LANES>: SupportedLaneCount,

🔬This is a nightly-only experimental API. (portable_simd #86656)

Splits a slice into a prefix, a middle of aligned SIMD types, and a suffix.

This is a safe wrapper around slice::align_to, so inherits the same guarantees as that method.

Panics

This will panic if the size of the SIMD type is different from LANES times that of the scalar.

At the time of writing, the trait restrictions on Simd<T, LANES> keeps that from ever happening, as only power-of-two numbers of lanes are supported. It’s possible that, in the future, those restrictions might be lifted in a way that would make it possible to see panics from this method for something like LANES == 3.

Examples

#![feature(portable_simd)]
use core::simd::prelude::*;

let short = &[1, 2, 3];
let (prefix, middle, suffix) = short.as_simd::<4>();
assert_eq!(middle, []); // Not enough elements for anything in the middle

// They might be split in any possible way between prefix and suffix
let it = prefix.iter().chain(suffix).copied();
assert_eq!(it.collect::<Vec<_>>(), vec![1, 2, 3]);

fn basic_simd_sum(x: &[f32]) -> f32 {
    use std::ops::Add;
    let (prefix, middle, suffix) = x.as_simd();
    let sums = f32x4::from_array([
        prefix.iter().copied().sum(),
        0.0,
        0.0,
        suffix.iter().copied().sum(),
    ]);
    let sums = middle.iter().copied().fold(sums, f32x4::add);
    sums.reduce_sum()
}

let numbers: Vec<f32> = (1..101).map(|x| x as _).collect();
assert_eq!(basic_simd_sum(&numbers[1..99]), 4949.0);

pub fn as_simd_mut<const LANES: usize>( &mut self, ) -> (&mut [T], &mut [Simd<T, LANES>], &mut [T])

where Simd<T, LANES>: AsMut<[T; LANES]>, T: SimdElement, LaneCount<LANES>: SupportedLaneCount,

🔬This is a nightly-only experimental API. (portable_simd #86656)

Splits a mutable slice into a mutable prefix, a middle of aligned SIMD types, and a mutable suffix.

This is a safe wrapper around slice::align_to_mut, so inherits the same guarantees as that method.

This is the mutable version of slice::as_simd; see that for examples.

Panics

This will panic if the size of the SIMD type is different from LANES times that of the scalar.

At the time of writing, the trait restrictions on Simd<T, LANES> keeps that from ever happening, as only power-of-two numbers of lanes are supported. It’s possible that, in the future, those restrictions might be lifted in a way that would make it possible to see panics from this method for something like LANES == 3.

pub fn is_sorted(&self) -> bool

where T: PartialOrd,

Checks if the elements of this slice are sorted.

That is, for each element a and its following element b, a <= b must hold. If the slice yields exactly zero or one element, true is returned.

Note that if Self::Item is only PartialOrd, but not Ord, the above definition implies that this function returns false if any two consecutive items are not comparable.

Examples

let empty: [i32; 0] = [];

assert!([1, 2, 2, 9].is_sorted());
assert!(![1, 3, 2, 4].is_sorted());
assert!([0].is_sorted());
assert!(empty.is_sorted());
assert!(![0.0, 1.0, f32::NAN].is_sorted());

pub fn is_sorted_by<'a, F>(&'a self, compare: F) -> bool

where F: FnMut(&'a T, &'a T) -> bool,

Checks if the elements of this slice are sorted using the given comparator function.

Instead of using PartialOrd::partial_cmp, this function uses the given compare function to determine whether two elements are to be considered in sorted order.

Examples

assert!([1, 2, 2, 9].is_sorted_by(|a, b| a <= b));
assert!(![1, 2, 2, 9].is_sorted_by(|a, b| a < b));

assert!([0].is_sorted_by(|a, b| true));
assert!([0].is_sorted_by(|a, b| false));

let empty: [i32; 0] = [];
assert!(empty.is_sorted_by(|a, b| false));
assert!(empty.is_sorted_by(|a, b| true));

pub fn is_sorted_by_key<'a, F, K>(&'a self, f: F) -> bool

where F: FnMut(&'a T) -> K, K: PartialOrd,

Checks if the elements of this slice are sorted using the given key extraction function.

Instead of comparing the slice’s elements directly, this function compares the keys of the elements, as determined by f. Apart from that, it’s equivalent to is_sorted; see its documentation for more information.

Examples

assert!(["c", "bb", "aaa"].is_sorted_by_key(|s| s.len()));
assert!(![-2i32, -1, 0, 3].is_sorted_by_key(|n| n.abs()));

pub fn partition_point<P>(&self, pred: P) -> usize

where P: FnMut(&T) -> bool,

Returns the index of the partition point according to the given predicate (the index of the first element of the second partition).

The slice is assumed to be partitioned according to the given predicate. This means that all elements for which the predicate returns true are at the start of the slice and all elements for which the predicate returns false are at the end. For example, [7, 15, 3, 5, 4, 12, 6] is partitioned under the predicate x % 2 != 0 (all odd numbers are at the start, all even at the end).

If this slice is not partitioned, the returned result is unspecified and meaningless, as this method performs a kind of binary search.

See also binary_search, binary_search_by, and binary_search_by_key.

Examples

let v = [1, 2, 3, 3, 5, 6, 7];
let i = v.partition_point(|&x| x < 5);

assert_eq!(i, 4);
assert!(v[..i].iter().all(|&x| x < 5));
assert!(v[i..].iter().all(|&x| !(x < 5)));

If all elements of the slice match the predicate, including if the slice is empty, then the length of the slice will be returned:

let a = [2, 4, 8];
assert_eq!(a.partition_point(|x| x < &100), a.len());
let a: [i32; 0] = [];
assert_eq!(a.partition_point(|x| x < &100), 0);

If you want to insert an item to a sorted vector, while maintaining sort order:

let mut s = vec![0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55];
let num = 42;
let idx = s.partition_point(|&x| x <= num);
s.insert(idx, num);
assert_eq!(s, [0, 1, 1, 1, 1, 2, 3, 5, 8, 13, 21, 34, 42, 55]);

pub fn take<'a, R>(self: &mut &'a [T], range: R) -> Option<&'a [T]>

where R: OneSidedRange<usize>,

🔬This is a nightly-only experimental API. (slice_take #62280)

Removes the subslice corresponding to the given range and returns a reference to it.

Returns None and does not modify the slice if the given range is out of bounds.

Note that this method only accepts one-sided ranges such as 2.. or ..6, but not 2..6.

Examples

Taking the first three elements of a slice:

#![feature(slice_take)]

let mut slice: &[_] = &['a', 'b', 'c', 'd'];
let mut first_three = slice.take(..3).unwrap();

assert_eq!(slice, &['d']);
assert_eq!(first_three, &['a', 'b', 'c']);

Taking the last two elements of a slice:

#![feature(slice_take)]

let mut slice: &[_] = &['a', 'b', 'c', 'd'];
let mut tail = slice.take(2..).unwrap();

assert_eq!(slice, &['a', 'b']);
assert_eq!(tail, &['c', 'd']);

Getting None when range is out of bounds:

#![feature(slice_take)]

let mut slice: &[_] = &['a', 'b', 'c', 'd'];

assert_eq!(None, slice.take(5..));
assert_eq!(None, slice.take(..5));
assert_eq!(None, slice.take(..=4));
let expected: &[char] = &['a', 'b', 'c', 'd'];
assert_eq!(Some(expected), slice.take(..4));

pub fn take_mut<'a, R>(self: &mut &'a mut [T], range: R) -> Option<&'a mut [T]>

where R: OneSidedRange<usize>,

🔬This is a nightly-only experimental API. (slice_take #62280)

Removes the subslice corresponding to the given range and returns a mutable reference to it.

Returns None and does not modify the slice if the given range is out of bounds.

Note that this method only accepts one-sided ranges such as 2.. or ..6, but not 2..6.

Examples

Taking the first three elements of a slice:

#![feature(slice_take)]

let mut slice: &mut [_] = &mut ['a', 'b', 'c', 'd'];
let mut first_three = slice.take_mut(..3).unwrap();

assert_eq!(slice, &mut ['d']);
assert_eq!(first_three, &mut ['a', 'b', 'c']);

Taking the last two elements of a slice:

#![feature(slice_take)]

let mut slice: &mut [_] = &mut ['a', 'b', 'c', 'd'];
let mut tail = slice.take_mut(2..).unwrap();

assert_eq!(slice, &mut ['a', 'b']);
assert_eq!(tail, &mut ['c', 'd']);

Getting None when range is out of bounds:

#![feature(slice_take)]

let mut slice: &mut [_] = &mut ['a', 'b', 'c', 'd'];

assert_eq!(None, slice.take_mut(5..));
assert_eq!(None, slice.take_mut(..5));
assert_eq!(None, slice.take_mut(..=4));
let expected: &mut [_] = &mut ['a', 'b', 'c', 'd'];
assert_eq!(Some(expected), slice.take_mut(..4));

pub fn take_first<'a>(self: &mut &'a [T]) -> Option<&'a T>

🔬This is a nightly-only experimental API. (slice_take #62280)

Removes the first element of the slice and returns a reference to it.

Returns None if the slice is empty.

Examples

#![feature(slice_take)]

let mut slice: &[_] = &['a', 'b', 'c'];
let first = slice.take_first().unwrap();

assert_eq!(slice, &['b', 'c']);
assert_eq!(first, &'a');

pub fn take_first_mut<'a>(self: &mut &'a mut [T]) -> Option<&'a mut T>

🔬This is a nightly-only experimental API. (slice_take #62280)

Removes the first element of the slice and returns a mutable reference to it.

Returns None if the slice is empty.

Examples

#![feature(slice_take)]

let mut slice: &mut [_] = &mut ['a', 'b', 'c'];
let first = slice.take_first_mut().unwrap();
*first = 'd';

assert_eq!(slice, &['b', 'c']);
assert_eq!(first, &'d');

pub fn take_last<'a>(self: &mut &'a [T]) -> Option<&'a T>

🔬This is a nightly-only experimental API. (slice_take #62280)

Removes the last element of the slice and returns a reference to it.

Returns None if the slice is empty.

Examples

#![feature(slice_take)]

let mut slice: &[_] = &['a', 'b', 'c'];
let last = slice.take_last().unwrap();

assert_eq!(slice, &['a', 'b']);
assert_eq!(last, &'c');

pub fn take_last_mut<'a>(self: &mut &'a mut [T]) -> Option<&'a mut T>

🔬This is a nightly-only experimental API. (slice_take #62280)

Removes the last element of the slice and returns a mutable reference to it.

Returns None if the slice is empty.

Examples

#![feature(slice_take)]

let mut slice: &mut [_] = &mut ['a', 'b', 'c'];
let last = slice.take_last_mut().unwrap();
*last = 'd';

assert_eq!(slice, &['a', 'b']);
assert_eq!(last, &'d');

pub unsafe fn get_many_unchecked_mut<I, const N: usize>( &mut self, indices: [I; N], ) -> [&mut <I as SliceIndex<[T]>>::Output; N]

where I: GetManyMutIndex + SliceIndex<[T]>,

🔬This is a nightly-only experimental API. (get_many_mut #104642)

Returns mutable references to many indices at once, without doing any checks.

An index can be either a usize, a Range or a RangeInclusive. Note that this method takes an array, so all indices must be of the same type. If passed an array of usizes this method gives back an array of mutable references to single elements, while if passed an array of ranges it gives back an array of mutable references to slices.

For a safe alternative see get_many_mut.

Safety

Calling this method with overlapping or out-of-bounds indices is undefined behavior even if the resulting references are not used.

Examples

#![feature(get_many_mut)]

let x = &mut [1, 2, 4];

unsafe {
    let [a, b] = x.get_many_unchecked_mut([0, 2]);
    *a *= 10;
    *b *= 100;
}
assert_eq!(x, &[10, 2, 400]);

unsafe {
    let [a, b] = x.get_many_unchecked_mut([0..1, 1..3]);
    a[0] = 8;
    b[0] = 88;
    b[1] = 888;
}
assert_eq!(x, &[8, 88, 888]);

unsafe {
    let [a, b] = x.get_many_unchecked_mut([1..=2, 0..=0]);
    a[0] = 11;
    a[1] = 111;
    b[0] = 1;
}
assert_eq!(x, &[1, 11, 111]);

pub fn get_many_mut<I, const N: usize>( &mut self, indices: [I; N], ) -> Result<[&mut <I as SliceIndex<[T]>>::Output; N], GetManyMutError>

where I: GetManyMutIndex + SliceIndex<[T]>,

🔬This is a nightly-only experimental API. (get_many_mut #104642)

Returns mutable references to many indices at once.

An index can be either a usize, a Range or a RangeInclusive. Note that this method takes an array, so all indices must be of the same type. If passed an array of usizes this method gives back an array of mutable references to single elements, while if passed an array of ranges it gives back an array of mutable references to slices.

Returns an error if any index is out-of-bounds, or if there are overlapping indices. An empty range is not considered to overlap if it is located at the beginning or at the end of another range, but is considered to overlap if it is located in the middle.

This method does a O(n^2) check to check that there are no overlapping indices, so be careful when passing many indices.

Examples

#![feature(get_many_mut)]

let v = &mut [1, 2, 3];
if let Ok([a, b]) = v.get_many_mut([0, 2]) {
    *a = 413;
    *b = 612;
}
assert_eq!(v, &[413, 2, 612]);

if let Ok([a, b]) = v.get_many_mut([0..1, 1..3]) {
    a[0] = 8;
    b[0] = 88;
    b[1] = 888;
}
assert_eq!(v, &[8, 88, 888]);

if let Ok([a, b]) = v.get_many_mut([1..=2, 0..=0]) {
    a[0] = 11;
    a[1] = 111;
    b[0] = 1;
}
assert_eq!(v, &[1, 11, 111]);

pub fn elem_offset(&self, element: &T) -> Option<usize>

🔬This is a nightly-only experimental API. (substr_range #126769)

Returns the index that an element reference points to.

Returns None if element does not point within the slice or if it points between elements.

This method is useful for extending slice iterators like slice::split.

Note that this uses pointer arithmetic and does not compare elements. To find the index of an element via comparison, use .iter().position() instead.

Panics

Panics if T is zero-sized.

Examples

Basic usage:

#![feature(substr_range)]

let nums: &[u32] = &[1, 7, 1, 1];
let num = &nums[2];

assert_eq!(num, &1);
assert_eq!(nums.elem_offset(num), Some(2));

Returning None with an in-between element:

#![feature(substr_range)]

let arr: &[[u32; 2]] = &[[0, 1], [2, 3]];
let flat_arr: &[u32] = arr.as_flattened();

let ok_elm: &[u32; 2] = flat_arr[0..2].try_into().unwrap();
let weird_elm: &[u32; 2] = flat_arr[1..3].try_into().unwrap();

assert_eq!(ok_elm, &[0, 1]);
assert_eq!(weird_elm, &[1, 2]);

assert_eq!(arr.elem_offset(ok_elm), Some(0)); // Points to element 0
assert_eq!(arr.elem_offset(weird_elm), None); // Points between element 0 and 1

pub fn subslice_range(&self, subslice: &[T]) -> Option<Range<usize>>

🔬This is a nightly-only experimental API. (substr_range #126769)

Returns the range of indices that a subslice points to.

Returns None if subslice does not point within the slice or if it points between elements.

This method does not compare elements. Instead, this method finds the location in the slice that subslice was obtained from. To find the index of a subslice via comparison, instead use .windows().position().

This method is useful for extending slice iterators like slice::split.

Note that this may return a false positive (either Some(0..0) or Some(self.len()..self.len())) if subslice has a length of zero and points to the beginning or end of another, separate, slice.

Panics

Panics if T is zero-sized.

Examples

Basic usage:

#![feature(substr_range)]

let nums = &[0, 5, 10, 0, 0, 5];

let mut iter = nums
    .split(|t| *t == 0)
    .map(|n| nums.subslice_range(n).unwrap());

assert_eq!(iter.next(), Some(0..0));
assert_eq!(iter.next(), Some(1..3));
assert_eq!(iter.next(), Some(4..4));
assert_eq!(iter.next(), Some(5..6));

impl<T, const N: usize> [[T; N]]

pub fn as_flattened(&self) -> &[T]

Takes a &[[T; N]], and flattens it to a &[T].

Panics

This panics if the length of the resulting slice would overflow a usize.

This is only possible when flattening a slice of arrays of zero-sized types, and thus tends to be irrelevant in practice. If size_of::<T>() > 0, this will never panic.

Examples

assert_eq!([[1, 2, 3], [4, 5, 6]].as_flattened(), &[1, 2, 3, 4, 5, 6]);

assert_eq!(
    [[1, 2, 3], [4, 5, 6]].as_flattened(),
    [[1, 2], [3, 4], [5, 6]].as_flattened(),
);

let slice_of_empty_arrays: &[[i32; 0]] = &[[], [], [], [], []];
assert!(slice_of_empty_arrays.as_flattened().is_empty());

let empty_slice_of_arrays: &[[u32; 10]] = &[];
assert!(empty_slice_of_arrays.as_flattened().is_empty());

pub fn as_flattened_mut(&mut self) -> &mut [T]

Takes a &mut [[T; N]], and flattens it to a &mut [T].

Panics

This panics if the length of the resulting slice would overflow a usize.

This is only possible when flattening a slice of arrays of zero-sized types, and thus tends to be irrelevant in practice. If size_of::<T>() > 0, this will never panic.

Examples

fn add_5_to_all(slice: &mut [i32]) {
    for i in slice {
        *i += 5;
    }
}

let mut array = [[1, 2, 3], [4, 5, 6], [7, 8, 9]];
add_5_to_all(array.as_flattened_mut());
assert_eq!(array, [[6, 7, 8], [9, 10, 11], [12, 13, 14]]);

impl [f32]

pub fn sort_floats(&mut self)

🔬This is a nightly-only experimental API. (sort_floats #93396)

Sorts the slice of floats.

This sort is in-place (i.e. does not allocate), O(n * log(n)) worst-case, and uses the ordering defined by f32::total_cmp.

Current implementation

This uses the same sorting algorithm as sort_unstable_by.

Examples

#![feature(sort_floats)]
let mut v = [2.6, -5e-8, f32::NAN, 8.29, f32::INFINITY, -1.0, 0.0, -f32::INFINITY, -0.0];

v.sort_floats();
let sorted = [-f32::INFINITY, -1.0, -5e-8, -0.0, 0.0, 2.6, 8.29, f32::INFINITY, f32::NAN];
assert_eq!(&v[..8], &sorted[..8]);
assert!(v[8].is_nan());

impl [f64]

pub fn sort_floats(&mut self)

🔬This is a nightly-only experimental API. (sort_floats #93396)

Sorts the slice of floats.

This sort is in-place (i.e. does not allocate), O(n * log(n)) worst-case, and uses the ordering defined by f64::total_cmp.

Current implementation

This uses the same sorting algorithm as sort_unstable_by.

Examples

#![feature(sort_floats)]
let mut v = [2.6, -5e-8, f64::NAN, 8.29, f64::INFINITY, -1.0, 0.0, -f64::INFINITY, -0.0];

v.sort_floats();
let sorted = [-f64::INFINITY, -1.0, -5e-8, -0.0, 0.0, 2.6, 8.29, f64::INFINITY, f64::NAN];
assert_eq!(&v[..8], &sorted[..8]);
assert!(v[8].is_nan());

impl [u8]

pub fn utf8_chunks(&self) -> Utf8Chunks<'_>

Creates an iterator over the contiguous valid UTF-8 ranges of this slice, and the non-UTF-8 fragments in between.

See the Utf8Chunk type for documenation of the items yielded by this iterator.

Examples

This function formats arbitrary but mostly-UTF-8 bytes into Rust source code in the form of a C-string literal (c"...").

use std::fmt::Write as _;

pub fn cstr_literal(bytes: &[u8]) -> String {
    let mut repr = String::new();
    repr.push_str("c\"");
    for chunk in bytes.utf8_chunks() {
        for ch in chunk.valid().chars() {
            // Escapes \0, \t, \r, \n, \\, \', \", and uses \u{...} for non-printable characters.
            write!(repr, "{}", ch.escape_debug()).unwrap();
        }
        for byte in chunk.invalid() {
            write!(repr, "\\x{:02X}", byte).unwrap();
        }
    }
    repr.push('"');
    repr
}

fn main() {
    let lit = cstr_literal(b"\xferris the \xf0\x9f\xa6\x80\x07");
    let expected = stringify!(c"\xFErris the 🦀\u{7}");
    assert_eq!(lit, expected);
}

impl<T> [T]

pub fn sort(&mut self)

where T: Ord,

Sorts the slice, preserving initial order of equal elements.

This sort is stable (i.e., does not reorder equal elements) and O(n * log(n)) worst-case.

If the implementation of Ord for T does not implement a total order, the function may panic; even if the function exits normally, the resulting order of elements in the slice is unspecified. See also the note on panicking below.

When applicable, unstable sorting is preferred because it is generally faster than stable sorting and it doesn’t allocate auxiliary memory. See sort_unstable. The exception are partially sorted slices, which may be better served with slice::sort.

Sorting types that only implement PartialOrd such as f32 and f64 require additional precautions. For example, f32::NAN != f32::NAN, which doesn’t fulfill the reflexivity requirement of Ord. By using an alternative comparison function with slice::sort_by such as f32::total_cmp or f64::total_cmp that defines a total order users can sort slices containing floating-point values. Alternatively, if all values in the slice are guaranteed to be in a subset for which PartialOrd::partial_cmp forms a total order, it’s possible to sort the slice with sort_by(|a, b| a.partial_cmp(b).unwrap()).

Current implementation

The current implementation is based on driftsort by Orson Peters and Lukas Bergdoll, which combines the fast average case of quicksort with the fast worst case and partial run detection of mergesort, achieving linear time on fully sorted and reversed inputs. On inputs with k distinct elements, the expected time to sort the data is O(n * log(k)).

The auxiliary memory allocation behavior depends on the input length. Short slices are handled without allocation, medium sized slices allocate self.len() and beyond that it clamps at self.len() / 2.

Panics

May panic if the implementation of Ord for T does not implement a total order, or if the Ord implementation itself panics.

All safe functions on slices preserve the invariant that even if the function panics, all original elements will remain in the slice and any possible modifications via interior mutability are observed in the input. This ensures that recovery code (for instance inside of a Drop or following a catch_unwind) will still have access to all the original elements. For instance, if the slice belongs to a Vec, the Vec::drop method will be able to dispose of all contained elements.

Examples

let mut v = [4, -5, 1, -3, 2];

v.sort();
assert_eq!(v, [-5, -3, 1, 2, 4]);

pub fn sort_by<F>(&mut self, compare: F)

where F: FnMut(&T, &T) -> Ordering,

Sorts the slice with a comparison function, preserving initial order of equal elements.

This sort is stable (i.e., does not reorder equal elements) and O(n * log(n)) worst-case.

If the comparison function compare does not implement a total order, the function may panic; even if the function exits normally, the resulting order of elements in the slice is unspecified. See also the note on panicking below.

For example |a, b| (a - b).cmp(a) is a comparison function that is neither transitive nor reflexive nor total, a < b < c < a with a = 1, b = 2, c = 3. For more information and examples see the Ord documentation.

Current implementation

The current implementation is based on driftsort by Orson Peters and Lukas Bergdoll, which combines the fast average case of quicksort with the fast worst case and partial run detection of mergesort, achieving linear time on fully sorted and reversed inputs. On inputs with k distinct elements, the expected time to sort the data is O(n * log(k)).

The auxiliary memory allocation behavior depends on the input length. Short slices are handled without allocation, medium sized slices allocate self.len() and beyond that it clamps at self.len() / 2.

Panics

May panic if compare does not implement a total order, or if compare itself panics.

All safe functions on slices preserve the invariant that even if the function panics, all original elements will remain in the slice and any possible modifications via interior mutability are observed in the input. This ensures that recovery code (for instance inside of a Drop or following a catch_unwind) will still have access to all the original elements. For instance, if the slice belongs to a Vec, the Vec::drop method will be able to dispose of all contained elements.

Examples

let mut v = [4, -5, 1, -3, 2];
v.sort_by(|a, b| a.cmp(b));
assert_eq!(v, [-5, -3, 1, 2, 4]);

// reverse sorting
v.sort_by(|a, b| b.cmp(a));
assert_eq!(v, [4, 2, 1, -3, -5]);

pub fn sort_by_key<K, F>(&mut self, f: F)

where F: FnMut(&T) -> K, K: Ord,

Sorts the slice with a key extraction function, preserving initial order of equal elements.

This sort is stable (i.e., does not reorder equal elements) and O(m * n * log(n)) worst-case, where the key function is O(m).

If the implementation of Ord for K does not implement a total order, the function may panic; even if the function exits normally, the resulting order of elements in the slice is unspecified. See also the note on panicking below.

Current implementation

The current implementation is based on driftsort by Orson Peters and Lukas Bergdoll, which combines the fast average case of quicksort with the fast worst case and partial run detection of mergesort, achieving linear time on fully sorted and reversed inputs. On inputs with k distinct elements, the expected time to sort the data is O(n * log(k)).

The auxiliary memory allocation behavior depends on the input length. Short slices are handled without allocation, medium sized slices allocate self.len() and beyond that it clamps at self.len() / 2.

Panics

May panic if the implementation of Ord for K does not implement a total order, or if the Ord implementation or the key-function f panics.

All safe functions on slices preserve the invariant that even if the function panics, all original elements will remain in the slice and any possible modifications via interior mutability are observed in the input. This ensures that recovery code (for instance inside of a Drop or following a catch_unwind) will still have access to all the original elements. For instance, if the slice belongs to a Vec, the Vec::drop method will be able to dispose of all contained elements.

Examples

let mut v = [4i32, -5, 1, -3, 2];

v.sort_by_key(|k| k.abs());
assert_eq!(v, [1, 2, -3, 4, -5]);

pub fn sort_by_cached_key<K, F>(&mut self, f: F)

where F: FnMut(&T) -> K, K: Ord,

Sorts the slice with a key extraction function, preserving initial order of equal elements.

This sort is stable (i.e., does not reorder equal elements) and O(m * n + n * log(n)) worst-case, where the key function is O(m).

During sorting, the key function is called at most once per element, by using temporary storage to remember the results of key evaluation. The order of calls to the key function is unspecified and may change in future versions of the standard library.

If the implementation of Ord for K does not implement a total order, the function may panic; even if the function exits normally, the resulting order of elements in the slice is unspecified. See also the note on panicking below.

For simple key functions (e.g., functions that are property accesses or basic operations), sort_by_key is likely to be faster.

Current implementation

The current implementation is based on instruction-parallel-network sort by Lukas Bergdoll, which combines the fast average case of randomized quicksort with the fast worst case of heapsort, while achieving linear time on fully sorted and reversed inputs. And O(k * log(n)) where k is the number of distinct elements in the input. It leverages superscalar out-of-order execution capabilities commonly found in CPUs, to efficiently perform the operation.

In the worst case, the algorithm allocates temporary storage in a Vec<(K, usize)> the length of the slice.

Panics

May panic if the implementation of Ord for K does not implement a total order, or if the Ord implementation panics.

All safe functions on slices preserve the invariant that even if the function panics, all original elements will remain in the slice and any possible modifications via interior mutability are observed in the input. This ensures that recovery code (for instance inside of a Drop or following a catch_unwind) will still have access to all the original elements. For instance, if the slice belongs to a Vec, the Vec::drop method will be able to dispose of all contained elements.

Examples

let mut v = [4i32, -5, 1, -3, 2, 10];

// Strings are sorted by lexicographical order.
v.sort_by_cached_key(|k| k.to_string());
assert_eq!(v, [-3, -5, 1, 10, 2, 4]);

pub fn to_vec(&self) -> Vec<T>

where T: Clone,

Copies self into a new Vec.

Examples

let s = [10, 40, 30];
let x = s.to_vec();
// Here, `s` and `x` can be modified independently.

pub fn to_vec_in<A>(&self, alloc: A) -> Vec<T, A>

where A: Allocator, T: Clone,

🔬This is a nightly-only experimental API. (allocator_api #32838)

Copies self into a new Vec with an allocator.

Examples

#![feature(allocator_api)]

use std::alloc::System;

let s = [10, 40, 30];
let x = s.to_vec_in(System);
// Here, `s` and `x` can be modified independently.

pub fn into_vec<A>(self: Box<[T], A>) -> Vec<T, A>

where A: Allocator,

Converts self into a vector without clones or allocation.

The resulting vector can be converted back into a box via Vec<T>’s into_boxed_slice method.

Examples

let s: Box<[i32]> = Box::new([10, 40, 30]);
let x = s.into_vec();
// `s` cannot be used anymore because it has been converted into `x`.

assert_eq!(x, vec![10, 40, 30]);

pub fn repeat(&self, n: usize) -> Vec<T>

where T: Copy,

Creates a vector by copying a slice n times.

Panics

This function will panic if the capacity would overflow.

Examples

Basic usage:

assert_eq!([1, 2].repeat(3), vec![1, 2, 1, 2, 1, 2]);

A panic upon overflow:

// this will panic at runtime
b"0123456789abcdef".repeat(usize::MAX);

pub fn concat<Item>(&self) -> <[T] as Concat<Item>>::Output

where [T]: Concat<Item>, Item: ?Sized,

Flattens a slice of T into a single value Self::Output.

Examples

assert_eq!(["hello", "world"].concat(), "helloworld");
assert_eq!([[1, 2], [3, 4]].concat(), [1, 2, 3, 4]);

pub fn join<Separator>( &self, sep: Separator, ) -> <[T] as Join<Separator>>::Output

where [T]: Join<Separator>,

Flattens a slice of T into a single value Self::Output, placing a given separator between each.

Examples

assert_eq!(["hello", "world"].join(" "), "hello world");
assert_eq!([[1, 2], [3, 4]].join(&0), [1, 2, 0, 3, 4]);
assert_eq!([[1, 2], [3, 4]].join(&[0, 0][..]), [1, 2, 0, 0, 3, 4]);

pub fn connect<Separator>( &self, sep: Separator, ) -> <[T] as Join<Separator>>::Output

where [T]: Join<Separator>,

👎Deprecated since 1.3.0: renamed to join

Flattens a slice of T into a single value Self::Output, placing a given separator between each.

Examples

assert_eq!(["hello", "world"].connect(" "), "hello world");
assert_eq!([[1, 2], [3, 4]].connect(&0), [1, 2, 0, 3, 4]);

impl [u8]

pub fn to_ascii_uppercase(&self) -> Vec<u8>

Returns a vector containing a copy of this slice where each byte is mapped to its ASCII upper case equivalent.

ASCII letters ‘a’ to ‘z’ are mapped to ‘A’ to ‘Z’, but non-ASCII letters are unchanged.

To uppercase the value in-place, use make_ascii_uppercase.

pub fn to_ascii_lowercase(&self) -> Vec<u8>

Returns a vector containing a copy of this slice where each byte is mapped to its ASCII lower case equivalent.

ASCII letters ‘A’ to ‘Z’ are mapped to ‘a’ to ‘z’, but non-ASCII letters are unchanged.

To lowercase the value in-place, use make_ascii_lowercase.

Trait Implementations

impl<T> AsMut<[T]> for [T]

fn as_mut(&mut self) -> &mut [T]

Converts this type into a mutable reference of the (usually inferred) input type.

impl<T, const N: usize> AsMut<[T]> for [T; N]

fn as_mut(&mut self) -> &mut [T]

Converts this type into a mutable reference of the (usually inferred) input type.

impl<T, const N: usize> AsMut<[T]> for Simd<T, N>

where LaneCount<N>: SupportedLaneCount, T: SimdElement,

fn as_mut(&mut self) -> &mut [T]

Converts this type into a mutable reference of the (usually inferred) input type.

impl<T, A> AsMut<[T]> for Vec<T, A>

where A: Allocator,

fn as_mut(&mut self) -> &mut [T]

Converts this type into a mutable reference of the (usually inferred) input type.

impl<T> AsRef<[T]> for [T]

fn as_ref(&self) -> &[T]

Converts this type into a shared reference of the (usually inferred) input type.

impl<T, const N: usize> AsRef<[T]> for [T; N]

fn as_ref(&self) -> &[T]

Converts this type into a shared reference of the (usually inferred) input type.

impl<'a, T, A> AsRef<[T]> for Drain<'a, T, A>

where A: Allocator,

fn as_ref(&self) -> &[T]

Converts this type into a shared reference of the (usually inferred) input type.

impl<T, A> AsRef<[T]> for IntoIter<T, A>

where A: Allocator,

fn as_ref(&self) -> &[T]

Converts this type into a shared reference of the (usually inferred) input type.

impl<T> AsRef<[T]> for Iter<'_, T>

fn as_ref(&self) -> &[T]

Converts this type into a shared reference of the (usually inferred) input type.

impl<T> AsRef<[T]> for IterMut<'_, T>

fn as_ref(&self) -> &[T]

Converts this type into a shared reference of the (usually inferred) input type.

impl<T, const N: usize> AsRef<[T]> for Simd<T, N>

where LaneCount<N>: SupportedLaneCount, T: SimdElement,

fn as_ref(&self) -> &[T]

Converts this type into a shared reference of the (usually inferred) input type.

impl<T, A> AsRef<[T]> for Vec<T, A>

where A: Allocator,

fn as_ref(&self) -> &[T]

Converts this type into a shared reference of the (usually inferred) input type.

impl<'a> AsRef<[u8]> for Drain<'a>

fn as_ref(&self) -> &[u8]

Converts this type into a shared reference of the (usually inferred) input type.

impl AsRef<[u8]> for String

fn as_ref(&self) -> &[u8]

Converts this type into a shared reference of the (usually inferred) input type.

impl AsRef<[u8]> for str

fn as_ref(&self) -> &[u8]

Converts this type into a shared reference of the (usually inferred) input type.

impl AsciiExt for [u8]

type Owned = Vec<u8>

👎Deprecated since 1.26.0: use inherent methods instead

Container type for copied ASCII characters.

fn is_ascii(&self) -> bool

👎Deprecated since 1.26.0: use inherent methods instead

Checks if the value is within the ASCII range.

fn to_ascii_uppercase(&self) -> Self::Owned

👎Deprecated since 1.26.0: use inherent methods instead

Makes a copy of the value in its ASCII upper case equivalent.

fn to_ascii_lowercase(&self) -> Self::Owned

👎Deprecated since 1.26.0: use inherent methods instead

Makes a copy of the value in its ASCII lower case equivalent.

fn eq_ignore_ascii_case(&self, o: &Self) -> bool

👎Deprecated since 1.26.0: use inherent methods instead

Checks that two values are an ASCII case-insensitive match.

fn make_ascii_uppercase(&mut self)

👎Deprecated since 1.26.0: use inherent methods instead

Converts this type to its ASCII upper case equivalent in-place.

fn make_ascii_lowercase(&mut self)

👎Deprecated since 1.26.0: use inherent methods instead

Converts this type to its ASCII lower case equivalent in-place.

impl<T, const N: usize> Borrow<[T]> for [T; N]

fn borrow(&self) -> &[T]

Immutably borrows from an owned value.

impl<T, A> Borrow<[T]> for Vec<T, A>

where A: Allocator,

fn borrow(&self) -> &[T]

Immutably borrows from an owned value.

impl<T, const N: usize> BorrowMut<[T]> for [T; N]

fn borrow_mut(&mut self) -> &mut [T]

Mutably borrows from an owned value.

impl<T, A> BorrowMut<[T]> for Vec<T, A>

where A: Allocator,

fn borrow_mut(&mut self) -> &mut [T]

Mutably borrows from an owned value.

impl BufRead for &[u8]

fn fill_buf(&mut self) -> Result<&[u8]>

Returns the contents of the internal buffer, filling it with more data from the inner reader if it is empty.

fn consume(&mut self, amt: usize)

Tells this buffer that amt bytes have been consumed from the buffer, so they should no longer be returned in calls to read.

fn has_data_left(&mut self) -> Result<bool>

🔬This is a nightly-only experimental API. (buf_read_has_data_left #86423)

Checks if the underlying Read has any data left to be read.

fn read_until(&mut self, byte: u8, buf: &mut Vec<u8>) -> Result<usize>

Reads all bytes into buf until the delimiter byte or EOF is reached.

fn skip_until(&mut self, byte: u8) -> Result<usize>

Skips all bytes until the delimiter byte or EOF is reached.

fn read_line(&mut self, buf: &mut String) -> Result<usize>

Reads all bytes until a newline (the 0xA byte) is reached, and append them to the provided String buffer.

fn split(self, byte: u8) -> Split<Self>

where Self: Sized,

Returns an iterator over the contents of this reader split on the byte byte.

fn lines(self) -> Lines<Self>

where Self: Sized,

Returns an iterator over the lines of this reader.

impl<T, A> Clone for Box<[T], A>

where T: Clone, A: Allocator + Clone,

fn clone_from(&mut self, source: &Box<[T], A>)

Copies source’s contents into self without creating a new allocation, so long as the two are of the same length.

Examples

let x = Box::new([5, 6, 7]);
let mut y = Box::new([8, 9, 10]);
let yp: *const [i32] = &*y;

y.clone_from(&x);

// The value is the same
assert_eq!(x, y);

// And no allocation occurred
assert_eq!(yp, &*y);

fn clone(&self) -> Box<[T], A>

Returns a copy of the value.

impl<T> CloneToUninit for [T]

where T: Clone,

unsafe fn clone_to_uninit(&self, dst: *mut u8)

🔬This is a nightly-only experimental API. (clone_to_uninit #126799)

Performs copy-assignment from self to dst.

impl<T, V> Concat<T> for [V]

where T: Clone, V: Borrow<[T]>,

type Output = Vec<T>

🔬This is a nightly-only experimental API. (slice_concat_trait #27747)

The resulting type after concatenation

fn concat(slice: &[V]) -> Vec<T>

🔬This is a nightly-only experimental API. (slice_concat_trait #27747)

Implementation of [T]::concat

impl<S> Concat<str> for [S]

where S: Borrow<str>,

Note: str in Concat<str> is not meaningful here. This type parameter of the trait only exists to enable another impl.

type Output = String

🔬This is a nightly-only experimental API. (slice_concat_trait #27747)

The resulting type after concatenation

fn concat(slice: &[S]) -> String

🔬This is a nightly-only experimental API. (slice_concat_trait #27747)

Implementation of [T]::concat

impl<T> Debug for [T]

where T: Debug,

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<T> Default for &[T]

fn default() -> &[T]

Creates an empty slice.

impl<T> Default for &mut [T]

fn default() -> &mut [T]

Creates a mutable empty slice.

impl<T> Default for Box<[T]>

fn default() -> Box<[T]>

Returns the “default value” for a type.

impl<T> From<&[T]> for Arc<[T]>

where T: Clone,

fn from(v: &[T]) -> Arc<[T]>

Allocates a reference-counted slice and fills it by cloning v’s items.

Example

let original: &[i32] = &[1, 2, 3];
let shared: Arc<[i32]> = Arc::from(original);
assert_eq!(&[1, 2, 3], &shared[..]);

impl<T> From<&[T]> for Box<[T]>

where T: Clone,

fn from(slice: &[T]) -> Box<[T]>

Converts a &[T] into a Box<[T]>

This conversion allocates on the heap and performs a copy of slice and its contents.

Examples

// create a &[u8] which will be used to create a Box<[u8]>
let slice: &[u8] = &[104, 101, 108, 108, 111];
let boxed_slice: Box<[u8]> = Box::from(slice);

println!("{boxed_slice:?}");

impl<'a, T> From<&'a [T]> for Cow<'a, [T]>

where T: Clone,

fn from(s: &'a [T]) -> Cow<'a, [T]>

Creates a Borrowed variant of Cow from a slice.

This conversion does not allocate or clone the data.

impl<T> From<&[T]> for Rc<[T]>

where T: Clone,

fn from(v: &[T]) -> Rc<[T]>

Allocates a reference-counted slice and fills it by cloning v’s items.

Example

let original: &[i32] = &[1, 2, 3];
let shared: Rc<[i32]> = Rc::from(original);
assert_eq!(&[1, 2, 3], &shared[..]);

impl<T> From<&[T]> for Vec<T>

where T: Clone,

fn from(s: &[T]) -> Vec<T>

Allocates a Vec<T> and fills it by cloning s’s items.

Examples

assert_eq!(Vec::from(&[1, 2, 3][..]), vec![1, 2, 3]);

impl<'data> From<&'data mut [MaybeUninit<u8>]> for BorrowedBuf<'data>

Creates a new BorrowedBuf from an uninitialized buffer.

Use set_init if part of the buffer is known to be already initialized.

fn from(buf: &'data mut [MaybeUninit<u8>]) -> BorrowedBuf<'data>

Converts to this type from the input type.

impl<T> From<&mut [T]> for Arc<[T]>

where T: Clone,

fn from(v: &mut [T]) -> Arc<[T]>

Allocates a reference-counted slice and fills it by cloning v’s items.

Example

let mut original = [1, 2, 3];
let original: &mut [i32] = &mut original;
let shared: Arc<[i32]> = Arc::from(original);
assert_eq!(&[1, 2, 3], &shared[..]);

impl<T> From<&mut [T]> for Box<[T]>

where T: Clone,

fn from(slice: &mut [T]) -> Box<[T]>

Converts a &mut [T] into a Box<[T]>

This conversion allocates on the heap and performs a copy of slice and its contents.

Examples

// create a &mut [u8] which will be used to create a Box<[u8]>
let mut array = [104, 101, 108, 108, 111];
let slice: &mut [u8] = &mut array;
let boxed_slice: Box<[u8]> = Box::from(slice);

println!("{boxed_slice:?}");

impl<T> From<&mut [T]> for Rc<[T]>

where T: Clone,

fn from(v: &mut [T]) -> Rc<[T]>

Allocates a reference-counted slice and fills it by cloning v’s items.

Example

let mut original = [1, 2, 3];
let original: &mut [i32] = &mut original;
let shared: Rc<[i32]> = Rc::from(original);
assert_eq!(&[1, 2, 3], &shared[..]);

impl<T> From<&mut [T]> for Vec<T>

where T: Clone,

fn from(s: &mut [T]) -> Vec<T>

Allocates a Vec<T> and fills it by cloning s’s items.

Examples

assert_eq!(Vec::from(&mut [1, 2, 3][..]), vec![1, 2, 3]);

impl<'data> From<&'data mut [u8]> for BorrowedBuf<'data>

Creates a new BorrowedBuf from a fully initialized slice.

fn from(slice: &'data mut [u8]) -> BorrowedBuf<'data>

Converts to this type from the input type.

impl<T, const N: usize> From<[T; N]> for Box<[T]>

fn from(array: [T; N]) -> Box<[T]>

Converts a [T; N] into a Box<[T]>

This conversion moves the array to newly heap-allocated memory.

Examples

let boxed: Box<[u8]> = Box::from([4, 2]);
println!("{boxed:?}");

impl<A> From<Box<str, A>> for Box<[u8], A>

where A: Allocator,

fn from(s: Box<str, A>) -> Box<[u8], A>

Converts a Box<str> into a Box<[u8]>

This conversion does not allocate on the heap and happens in place.

Examples

// create a Box<str> which will be used to create a Box<[u8]>
let boxed: Box<str> = Box::from("hello");
let boxed_str: Box<[u8]> = Box::from(boxed);

// create a &[u8] which will be used to create a Box<[u8]>
let slice: &[u8] = &[104, 101, 108, 108, 111];
let boxed_slice = Box::from(slice);

assert_eq!(boxed_slice, boxed_str);

impl<T> From<Cow<'_, [T]>> for Box<[T]>

where T: Clone,

fn from(cow: Cow<'_, [T]>) -> Box<[T]>

Converts a Cow<'_, [T]> into a Box<[T]>

When cow is the Cow::Borrowed variant, this conversion allocates on the heap and copies the underlying slice. Otherwise, it will try to reuse the owned Vec’s allocation.

impl<T, A> From<Vec<T, A>> for Box<[T], A>

where A: Allocator,

fn from(v: Vec<T, A>) -> Box<[T], A>

Converts a vector into a boxed slice.

Before doing the conversion, this method discards excess capacity like Vec::shrink_to_fit.

Examples

assert_eq!(Box::from(vec![1, 2, 3]), vec![1, 2, 3].into_boxed_slice());

Any excess capacity is removed:

let mut vec = Vec::with_capacity(10);
vec.extend([1, 2, 3]);

assert_eq!(Box::from(vec), vec![1, 2, 3].into_boxed_slice());

impl<I> FromIterator<I> for Box<[I]>

fn from_iter<T>(iter: T) -> Box<[I]>

where T: IntoIterator<Item = I>,

Creates a value from an iterator.

impl<T> Hash for [T]

where T: Hash,

fn hash<H>(&self, state: &mut H)

where H: Hasher,

Feeds this value into the given Hasher.

impl<T, I> Index<I> for [T]

where I: SliceIndex<[T]>,

type Output = <I as SliceIndex<[T]>>::Output

The returned type after indexing.

fn index(&self, index: I) -> &<I as SliceIndex<[T]>>::Output

Performs the indexing (container[index]) operation.

impl<T, I> IndexMut<I> for [T]

where I: SliceIndex<[T]>,

fn index_mut(&mut self, index: I) -> &mut <I as SliceIndex<[T]>>::Output

Performs the mutable indexing (container[index]) operation.

impl<'a, T> IntoIterator for &'a [T]

type Item = &'a T

The type of the elements being iterated over.

type IntoIter = Iter<'a, T>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Iter<'a, T>

Creates an iterator from a value.

impl<'a, I, A> IntoIterator for &'a Box<[I], A>

where A: Allocator,

type IntoIter = Iter<'a, I>

Which kind of iterator are we turning this into?

type Item = &'a I

The type of the elements being iterated over.

fn into_iter(self) -> Iter<'a, I>

Creates an iterator from a value.

impl<'a, T> IntoIterator for &'a mut [T]

type Item = &'a mut T

The type of the elements being iterated over.

type IntoIter = IterMut<'a, T>

Which kind of iterator are we turning this into?

fn into_iter(self) -> IterMut<'a, T>

Creates an iterator from a value.

impl<'a, I, A> IntoIterator for &'a mut Box<[I], A>

where A: Allocator,

type IntoIter = IterMut<'a, I>

Which kind of iterator are we turning this into?

type Item = &'a mut I

The type of the elements being iterated over.

fn into_iter(self) -> IterMut<'a, I>

Creates an iterator from a value.

impl<I, A> IntoIterator for Box<[I], A>

where A: Allocator,

type IntoIter = IntoIter<I, A>

Which kind of iterator are we turning this into?

type Item = I

The type of the elements being iterated over.

fn into_iter(self) -> IntoIter<I, A>

Creates an iterator from a value.

impl<T, V> Join<&[T]> for [V]

where T: Clone, V: Borrow<[T]>,

type Output = Vec<T>

🔬This is a nightly-only experimental API. (slice_concat_trait #27747)

The resulting type after concatenation

fn join(slice: &[V], sep: &[T]) -> Vec<T>

🔬This is a nightly-only experimental API. (slice_concat_trait #27747)

Implementation of [T]::join

impl<S: Borrow<OsStr>> Join<&OsStr> for [S]

type Output = OsString

🔬This is a nightly-only experimental API. (slice_concat_trait #27747)

The resulting type after concatenation

fn join(slice: &Self, sep: &OsStr) -> OsString

🔬This is a nightly-only experimental API. (slice_concat_trait #27747)

Implementation of [T]::join

impl<T, V> Join<&T> for [V]

where T: Clone, V: Borrow<[T]>,

type Output = Vec<T>

🔬This is a nightly-only experimental API. (slice_concat_trait #27747)

The resulting type after concatenation

fn join(slice: &[V], sep: &T) -> Vec<T>

🔬This is a nightly-only experimental API. (slice_concat_trait #27747)

Implementation of [T]::join

impl<S> Join<&str> for [S]

where S: Borrow<str>,

type Output = String

🔬This is a nightly-only experimental API. (slice_concat_trait #27747)

The resulting type after concatenation

fn join(slice: &[S], sep: &str) -> String

🔬This is a nightly-only experimental API. (slice_concat_trait #27747)

Implementation of [T]::join

impl<T> Ord for [T]

where T: Ord,

Implements comparison of slices lexicographically.

fn cmp(&self, other: &[T]) -> Ordering

This method returns an Ordering between self and other.

impl<T, U, const N: usize> PartialEq<&[U]> for [T; N]

where T: PartialEq<U>,

fn eq(&self, other: &&[U]) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &&[U]) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T, U> PartialEq<&[U]> for Cow<'_, [T]>

where T: PartialEq<U> + Clone,

fn eq(&self, other: &&[U]) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &&[U]) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T, U, A> PartialEq<&[U]> for Vec<T, A>

where A: Allocator, T: PartialEq<U>,

fn eq(&self, other: &&[U]) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &&[U]) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T, U, A> PartialEq<&[U]> for VecDeque<T, A>

where A: Allocator, T: PartialEq<U>,

fn eq(&self, other: &&[U]) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T, U, const N: usize> PartialEq<&mut [U]> for [T; N]

where T: PartialEq<U>,

fn eq(&self, other: &&mut [U]) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &&mut [U]) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T, U> PartialEq<&mut [U]> for Cow<'_, [T]>

where T: PartialEq<U> + Clone,

fn eq(&self, other: &&mut [U]) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &&mut [U]) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T, U, A> PartialEq<&mut [U]> for Vec<T, A>

where A: Allocator, T: PartialEq<U>,

fn eq(&self, other: &&mut [U]) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &&mut [U]) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T, U, A> PartialEq<&mut [U]> for VecDeque<T, A>

where A: Allocator, T: PartialEq<U>,

fn eq(&self, other: &&mut [U]) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T, U> PartialEq<[U]> for [T]

where T: PartialEq<U>,

fn eq(&self, other: &[U]) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &[U]) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T, U, const N: usize> PartialEq<[U]> for [T; N]

where T: PartialEq<U>,

fn eq(&self, other: &[U]) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &[U]) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T, U, A> PartialEq<[U]> for Vec<T, A>

where A: Allocator, T: PartialEq<U>,

fn eq(&self, other: &[U]) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &[U]) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T, U, const N: usize> PartialEq<[U; N]> for &[T]

where T: PartialEq<U>,

fn eq(&self, other: &[U; N]) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &[U; N]) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T, U, const N: usize> PartialEq<[U; N]> for &mut [T]

where T: PartialEq<U>,

fn eq(&self, other: &[U; N]) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &[U; N]) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T, U, const N: usize> PartialEq<[U; N]> for [T]

where T: PartialEq<U>,

fn eq(&self, other: &[U; N]) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &[U; N]) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T, U, A> PartialEq<Vec<U, A>> for &[T]

where A: Allocator, T: PartialEq<U>,

fn eq(&self, other: &Vec<U, A>) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Vec<U, A>) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T, U, A> PartialEq<Vec<U, A>> for &mut [T]

where A: Allocator, T: PartialEq<U>,

fn eq(&self, other: &Vec<U, A>) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Vec<U, A>) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T, U, A> PartialEq<Vec<U, A>> for [T]

where A: Allocator, T: PartialEq<U>,

fn eq(&self, other: &Vec<U, A>) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Vec<U, A>) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T> PartialOrd for [T]

where T: PartialOrd,

Implements comparison of slices lexicographically.

fn partial_cmp(&self, other: &[T]) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl<'b> Pattern for &'b [char]

Searches for chars that are equal to any of the chars in the slice.

Examples

assert_eq!("Hello world".find(&['o', 'l'][..]), Some(2));
assert_eq!("Hello world".find(&['h', 'w'][..]), Some(6));

type Searcher<'a> = CharSliceSearcher<'a, 'b>

🔬This is a nightly-only experimental API. (pattern #27721)

Associated searcher for this pattern

fn into_searcher<'a>(self, haystack: &'a str) -> CharSliceSearcher<'a, 'b>

🔬This is a nightly-only experimental API. (pattern #27721)

Constructs the associated searcher from self and the haystack to search in.

fn is_contained_in<'a>(self, haystack: &'a str) -> bool

🔬This is a nightly-only experimental API. (pattern #27721)

Checks whether the pattern matches anywhere in the haystack

fn is_prefix_of<'a>(self, haystack: &'a str) -> bool

🔬This is a nightly-only experimental API. (pattern #27721)

Checks whether the pattern matches at the front of the haystack

fn strip_prefix_of<'a>(self, haystack: &'a str) -> Option<&'a str>

🔬This is a nightly-only experimental API. (pattern #27721)

Removes the pattern from the front of haystack, if it matches.

fn is_suffix_of<'a>(self, haystack: &'a str) -> bool

where CharSliceSearcher<'a, 'b>: ReverseSearcher<'a>,

🔬This is a nightly-only experimental API. (pattern #27721)

Checks whether the pattern matches at the back of the haystack

fn strip_suffix_of<'a>(self, haystack: &'a str) -> Option<&'a str>

where CharSliceSearcher<'a, 'b>: ReverseSearcher<'a>,

🔬This is a nightly-only experimental API. (pattern #27721)

Removes the pattern from the back of haystack, if it matches.

fn as_utf8_pattern(&self) -> Option<Utf8Pattern<'_>>

🔬This is a nightly-only experimental API. (pattern #27721)

Returns the pattern as utf-8 bytes if possible.

impl Read for &[u8]

Read is implemented for &[u8] by copying from the slice.

Note that reading updates the slice to point to the yet unread part. The slice will be empty when EOF is reached.

fn read(&mut self, buf: &mut [u8]) -> Result<usize>

Pull some bytes from this source into the specified buffer, returning how many bytes were read.

fn read_buf(&mut self, cursor: BorrowedCursor<'_>) -> Result<()>

🔬This is a nightly-only experimental API. (read_buf #78485)

Pull some bytes from this source into the specified buffer.

fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> Result<usize>

Like read, except that it reads into a slice of buffers.

fn is_read_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (can_vector #69941)

Determines if this Reader has an efficient read_vectored implementation.

fn read_exact(&mut self, buf: &mut [u8]) -> Result<()>

Reads the exact number of bytes required to fill buf.

fn read_buf_exact(&mut self, cursor: BorrowedCursor<'_>) -> Result<()>

🔬This is a nightly-only experimental API. (read_buf #78485)

Reads the exact number of bytes required to fill cursor.

fn read_to_end(&mut self, buf: &mut Vec<u8>) -> Result<usize>

Reads all bytes until EOF in this source, placing them into buf.

fn read_to_string(&mut self, buf: &mut String) -> Result<usize>

Reads all bytes until EOF in this source, appending them to buf.

fn by_ref(&mut self) -> &mut Self

where Self: Sized,

Creates a “by reference” adaptor for this instance of Read.

fn bytes(self) -> Bytes<Self>

where Self: Sized,

Transforms this Read instance to an Iterator over its bytes.

fn chain<R: Read>(self, next: R) -> Chain<Self, R>

where Self: Sized,

Creates an adapter which will chain this stream with another.

fn take(self, limit: u64) -> Take<Self>

where Self: Sized,

Creates an adapter which will read at most limit bytes from it.

impl<T> SliceIndex<[T]> for (Bound<usize>, Bound<usize>)

type Output = [T]

The output type returned by methods.

fn get( self, slice: &[T], ) -> Option<&<(Bound<usize>, Bound<usize>) as SliceIndex<[T]>>::Output>

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a shared reference to the output at this location, if in bounds.

fn get_mut( self, slice: &mut [T], ) -> Option<&mut <(Bound<usize>, Bound<usize>) as SliceIndex<[T]>>::Output>

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable reference to the output at this location, if in bounds.

unsafe fn get_unchecked( self, slice: *const [T], ) -> *const <(Bound<usize>, Bound<usize>) as SliceIndex<[T]>>::Output

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a pointer to the output at this location, without performing any bounds checking.

unsafe fn get_unchecked_mut( self, slice: *mut [T], ) -> *mut <(Bound<usize>, Bound<usize>) as SliceIndex<[T]>>::Output

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable pointer to the output at this location, without performing any bounds checking.

fn index( self, slice: &[T], ) -> &<(Bound<usize>, Bound<usize>) as SliceIndex<[T]>>::Output

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a shared reference to the output at this location, panicking if out of bounds.

fn index_mut( self, slice: &mut [T], ) -> &mut <(Bound<usize>, Bound<usize>) as SliceIndex<[T]>>::Output

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable reference to the output at this location, panicking if out of bounds.

impl<T> SliceIndex<[T]> for Range<usize>

The methods index and index_mut panic if:

• the start of the range is greater than the end of the range or
• the end of the range is out of bounds.

type Output = [T]

The output type returned by methods.

fn get(self, slice: &[T]) -> Option<&[T]>

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a shared reference to the output at this location, if in bounds.

fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]>

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable reference to the output at this location, if in bounds.

unsafe fn get_unchecked(self, slice: *const [T]) -> *const [T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a pointer to the output at this location, without performing any bounds checking.

unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut [T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable pointer to the output at this location, without performing any bounds checking.

fn index(self, slice: &[T]) -> &[T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a shared reference to the output at this location, panicking if out of bounds.

fn index_mut(self, slice: &mut [T]) -> &mut [T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable reference to the output at this location, panicking if out of bounds.

impl<T> SliceIndex<[T]> for Range<usize>

type Output = [T]

The output type returned by methods.

fn get(self, slice: &[T]) -> Option<&[T]>

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a shared reference to the output at this location, if in bounds.

fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]>

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable reference to the output at this location, if in bounds.

unsafe fn get_unchecked(self, slice: *const [T]) -> *const [T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a pointer to the output at this location, without performing any bounds checking.

unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut [T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable pointer to the output at this location, without performing any bounds checking.

fn index(self, slice: &[T]) -> &[T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a shared reference to the output at this location, panicking if out of bounds.

fn index_mut(self, slice: &mut [T]) -> &mut [T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable reference to the output at this location, panicking if out of bounds.

impl<T> SliceIndex<[T]> for RangeFrom<usize>

The methods index and index_mut panic if the start of the range is out of bounds.

type Output = [T]

The output type returned by methods.

fn get(self, slice: &[T]) -> Option<&[T]>

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a shared reference to the output at this location, if in bounds.

fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]>

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable reference to the output at this location, if in bounds.

unsafe fn get_unchecked(self, slice: *const [T]) -> *const [T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a pointer to the output at this location, without performing any bounds checking.

unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut [T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable pointer to the output at this location, without performing any bounds checking.

fn index(self, slice: &[T]) -> &[T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a shared reference to the output at this location, panicking if out of bounds.

fn index_mut(self, slice: &mut [T]) -> &mut [T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable reference to the output at this location, panicking if out of bounds.

impl<T> SliceIndex<[T]> for RangeFrom<usize>

type Output = [T]

The output type returned by methods.

fn get(self, slice: &[T]) -> Option<&[T]>

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a shared reference to the output at this location, if in bounds.

fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]>

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable reference to the output at this location, if in bounds.

unsafe fn get_unchecked(self, slice: *const [T]) -> *const [T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a pointer to the output at this location, without performing any bounds checking.

unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut [T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable pointer to the output at this location, without performing any bounds checking.

fn index(self, slice: &[T]) -> &[T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a shared reference to the output at this location, panicking if out of bounds.

fn index_mut(self, slice: &mut [T]) -> &mut [T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable reference to the output at this location, panicking if out of bounds.

impl<T> SliceIndex<[T]> for RangeFull

type Output = [T]

The output type returned by methods.

fn get(self, slice: &[T]) -> Option<&[T]>

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a shared reference to the output at this location, if in bounds.

fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]>

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable reference to the output at this location, if in bounds.

unsafe fn get_unchecked(self, slice: *const [T]) -> *const [T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a pointer to the output at this location, without performing any bounds checking.

unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut [T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable pointer to the output at this location, without performing any bounds checking.

fn index(self, slice: &[T]) -> &[T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a shared reference to the output at this location, panicking if out of bounds.

fn index_mut(self, slice: &mut [T]) -> &mut [T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable reference to the output at this location, panicking if out of bounds.

impl<T> SliceIndex<[T]> for RangeInclusive<usize>

The methods index and index_mut panic if:

• the end of the range is usize::MAX or
• the start of the range is greater than the end of the range or
• the end of the range is out of bounds.

type Output = [T]

The output type returned by methods.

fn get(self, slice: &[T]) -> Option<&[T]>

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a shared reference to the output at this location, if in bounds.

fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]>

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable reference to the output at this location, if in bounds.

unsafe fn get_unchecked(self, slice: *const [T]) -> *const [T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a pointer to the output at this location, without performing any bounds checking.

unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut [T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable pointer to the output at this location, without performing any bounds checking.

fn index(self, slice: &[T]) -> &[T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a shared reference to the output at this location, panicking if out of bounds.

fn index_mut(self, slice: &mut [T]) -> &mut [T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable reference to the output at this location, panicking if out of bounds.

impl<T> SliceIndex<[T]> for RangeInclusive<usize>

type Output = [T]

The output type returned by methods.

fn get(self, slice: &[T]) -> Option<&[T]>

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a shared reference to the output at this location, if in bounds.

fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]>

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable reference to the output at this location, if in bounds.

unsafe fn get_unchecked(self, slice: *const [T]) -> *const [T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a pointer to the output at this location, without performing any bounds checking.

unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut [T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable pointer to the output at this location, without performing any bounds checking.

fn index(self, slice: &[T]) -> &[T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a shared reference to the output at this location, panicking if out of bounds.

fn index_mut(self, slice: &mut [T]) -> &mut [T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable reference to the output at this location, panicking if out of bounds.

impl<T> SliceIndex<[T]> for RangeTo<usize>

The methods index and index_mut panic if the end of the range is out of bounds.

type Output = [T]

The output type returned by methods.

fn get(self, slice: &[T]) -> Option<&[T]>

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a shared reference to the output at this location, if in bounds.

fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]>

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable reference to the output at this location, if in bounds.

unsafe fn get_unchecked(self, slice: *const [T]) -> *const [T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a pointer to the output at this location, without performing any bounds checking.

unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut [T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable pointer to the output at this location, without performing any bounds checking.

fn index(self, slice: &[T]) -> &[T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a shared reference to the output at this location, panicking if out of bounds.

fn index_mut(self, slice: &mut [T]) -> &mut [T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable reference to the output at this location, panicking if out of bounds.

impl<T> SliceIndex<[T]> for RangeToInclusive<usize>

The methods index and index_mut panic if the end of the range is out of bounds.

type Output = [T]

The output type returned by methods.

fn get(self, slice: &[T]) -> Option<&[T]>

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a shared reference to the output at this location, if in bounds.

fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]>

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable reference to the output at this location, if in bounds.

unsafe fn get_unchecked(self, slice: *const [T]) -> *const [T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a pointer to the output at this location, without performing any bounds checking.

unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut [T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable pointer to the output at this location, without performing any bounds checking.

fn index(self, slice: &[T]) -> &[T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a shared reference to the output at this location, panicking if out of bounds.

fn index_mut(self, slice: &mut [T]) -> &mut [T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable reference to the output at this location, panicking if out of bounds.

impl<T> SliceIndex<[T]> for usize

The methods index and index_mut panic if the index is out of bounds.

type Output = T

The output type returned by methods.

fn get(self, slice: &[T]) -> Option<&T>

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a shared reference to the output at this location, if in bounds.

fn get_mut(self, slice: &mut [T]) -> Option<&mut T>

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable reference to the output at this location, if in bounds.

unsafe fn get_unchecked(self, slice: *const [T]) -> *const T

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a pointer to the output at this location, without performing any bounds checking.

unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut T

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable pointer to the output at this location, without performing any bounds checking.

fn index(self, slice: &[T]) -> &T

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a shared reference to the output at this location, panicking if out of bounds.

fn index_mut(self, slice: &mut [T]) -> &mut T

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable reference to the output at this location, panicking if out of bounds.

impl<T> SlicePattern for [T]

type Item = T

🔬This is a nightly-only experimental API. (slice_pattern #56345)

The element type of the slice being matched on.

fn as_slice(&self) -> &[<[T] as SlicePattern>::Item]

🔬This is a nightly-only experimental API. (slice_pattern #56345)

Currently, the consumers of SlicePattern need a slice.

impl<T> ToOwned for [T]

where T: Clone,

type Owned = Vec<T>

The resulting type after obtaining ownership.

fn to_owned(&self) -> Vec<T>

Creates owned data from borrowed data, usually by cloning.

fn clone_into(&self, target: &mut Vec<T>)

Uses borrowed data to replace owned data, usually by cloning.

impl<'a> ToSocketAddrs for &'a [SocketAddr]

type Iter = Cloned<Iter<'a, SocketAddr>>

Returned iterator over socket addresses which this type may correspond to.

fn to_socket_addrs(&self) -> Result<Self::Iter>

Converts this object to an iterator of resolved SocketAddrs.

impl<'a, T, const N: usize> TryFrom<&'a [T]> for &'a [T; N]

Tries to create an array ref &[T; N] from a slice ref &[T]. Succeeds if slice.len() == N.

let bytes: [u8; 3] = [1, 0, 2];

let bytes_head: &[u8; 2] = <&[u8; 2]>::try_from(&bytes[0..2]).unwrap();
assert_eq!(1, u16::from_le_bytes(*bytes_head));

let bytes_tail: &[u8; 2] = bytes[1..3].try_into().unwrap();
assert_eq!(512, u16::from_le_bytes(*bytes_tail));

type Error = TryFromSliceError

The type returned in the event of a conversion error.

fn try_from(slice: &'a [T]) -> Result<&'a [T; N], TryFromSliceError>

Performs the conversion.

impl<T, const N: usize> TryFrom<&[T]> for [T; N]

where T: Copy,

Tries to create an array [T; N] by copying from a slice &[T]. Succeeds if slice.len() == N.

let bytes: [u8; 3] = [1, 0, 2];

let bytes_head: [u8; 2] = <[u8; 2]>::try_from(&bytes[0..2]).unwrap();
assert_eq!(1, u16::from_le_bytes(bytes_head));

let bytes_tail: [u8; 2] = bytes[1..3].try_into().unwrap();
assert_eq!(512, u16::from_le_bytes(bytes_tail));

type Error = TryFromSliceError

The type returned in the event of a conversion error.

fn try_from(slice: &[T]) -> Result<[T; N], TryFromSliceError>

Performs the conversion.

impl<T, const N: usize> TryFrom<&[T]> for Simd<T, N>

where LaneCount<N>: SupportedLaneCount, T: SimdElement,

type Error = TryFromSliceError

The type returned in the event of a conversion error.

fn try_from(slice: &[T]) -> Result<Simd<T, N>, TryFromSliceError>

Performs the conversion.

impl<'a, T, const N: usize> TryFrom<&'a mut [T]> for &'a mut [T; N]

Tries to create a mutable array ref &mut [T; N] from a mutable slice ref &mut [T]. Succeeds if slice.len() == N.

let mut bytes: [u8; 3] = [1, 0, 2];

let bytes_head: &mut [u8; 2] = <&mut [u8; 2]>::try_from(&mut bytes[0..2]).unwrap();
assert_eq!(1, u16::from_le_bytes(*bytes_head));

let bytes_tail: &mut [u8; 2] = (&mut bytes[1..3]).try_into().unwrap();
assert_eq!(512, u16::from_le_bytes(*bytes_tail));

type Error = TryFromSliceError

The type returned in the event of a conversion error.

fn try_from(slice: &'a mut [T]) -> Result<&'a mut [T; N], TryFromSliceError>

Performs the conversion.

impl<T, const N: usize> TryFrom<&mut [T]> for [T; N]

where T: Copy,

Tries to create an array [T; N] by copying from a mutable slice &mut [T]. Succeeds if slice.len() == N.

let mut bytes: [u8; 3] = [1, 0, 2];

let bytes_head: [u8; 2] = <[u8; 2]>::try_from(&mut bytes[0..2]).unwrap();
assert_eq!(1, u16::from_le_bytes(bytes_head));

let bytes_tail: [u8; 2] = (&mut bytes[1..3]).try_into().unwrap();
assert_eq!(512, u16::from_le_bytes(bytes_tail));

type Error = TryFromSliceError

The type returned in the event of a conversion error.

fn try_from(slice: &mut [T]) -> Result<[T; N], TryFromSliceError>

Performs the conversion.

impl<T, const N: usize> TryFrom<&mut [T]> for Simd<T, N>

where LaneCount<N>: SupportedLaneCount, T: SimdElement,

type Error = TryFromSliceError

The type returned in the event of a conversion error.

fn try_from(slice: &mut [T]) -> Result<Simd<T, N>, TryFromSliceError>

Performs the conversion.

impl Write for &mut [u8]

Write is implemented for &mut [u8] by copying into the slice, overwriting its data.

Note that writing updates the slice to point to the yet unwritten part. The slice will be empty when it has been completely overwritten.

If the number of bytes to be written exceeds the size of the slice, write operations will return short writes: ultimately, Ok(0); in this situation, write_all returns an error of kind ErrorKind::WriteZero.

fn write(&mut self, data: &[u8]) -> Result<usize>

Writes a buffer into this writer, returning how many bytes were written.

fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize>

Like write, except that it writes from a slice of buffers.

fn is_write_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (can_vector #69941)

Determines if this Writer has an efficient write_vectored implementation.

fn write_all(&mut self, data: &[u8]) -> Result<()>

Attempts to write an entire buffer into this writer.

fn flush(&mut self) -> Result<()>

Flushes this output stream, ensuring that all intermediately buffered contents reach their destination.

fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> Result<()>

🔬This is a nightly-only experimental API. (write_all_vectored #70436)

Attempts to write multiple buffers into this writer.

fn write_fmt(&mut self, fmt: Arguments<'_>) -> Result<()>

Writes a formatted string into this writer, returning any error encountered.

fn by_ref(&mut self) -> &mut Self

where Self: Sized,

Creates a “by reference” adapter for this instance of Write.

impl<T> Eq for [T]

where T: Eq,

impl<'a, I, A> !Iterator for &'a Box<[I], A>

where A: Allocator,

This implementation is required to make sure that the &Box<[I]>: IntoIterator implementation doesn’t overlap with IntoIterator for T where T: Iterator blanket.

impl<'a, I, A> !Iterator for &'a mut Box<[I], A>

where A: Allocator,

This implementation is required to make sure that the &mut Box<[I]>: IntoIterator implementation doesn’t overlap with IntoIterator for T where T: Iterator blanket.

impl<T> !Iterator for [T]

impl<I, A> !Iterator for Box<[I], A>

where A: Allocator,

This implementation is required to make sure that the Box<[I]>: IntoIterator implementation doesn’t overlap with IntoIterator for T where T: Iterator blanket.

impl<T> StructuralPartialEq for [T]

impl<T> UnsizedConstParamTy for [T]

where T: UnsizedConstParamTy,