std::weak_ptr<T>::expired
From cppreference.com
bool expired() const noexcept;
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(since C++11) (constexpr since C++26) |
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Checks if the managed object has already been deleted. The destructor for the managed object may not yet have been called, but this object's destruction is imminent (or may have already happened).
Return value
use_count() == 0
Notes
If the managed object is shared among threads, it is only meaningful when expired() returns true.
Example
Demonstrates how expired is used to check validity of the pointer.
Run this code
#include <iostream>
#include <memory>
std::weak_ptr<int> gw;
void f()
{
if (!gw.expired())
std::cout << "gw is valid\n";
else
std::cout << "gw is expired\n";
}
int main()
{
{
auto sp = std::make_shared<int>(42);
gw = sp;
f();
}
f();
}
Output:
gw is valid
gw is expired
See also
creates a shared_ptr that manages the referenced object (public member function) | |
returns the number of shared_ptr objects that manage the object (public member function) |