A fast and low allocation StringBuilder for .NET.

Install the package:

PM> Install-Package LinkDotNet.StringBuilder

Afterwards use the package as follow:

using LinkDotNet.StringBuilder; // Namespace of the package

ValueStringBuilder stringBuilder = new ValueStringBuilder();
stringBuilder.AppendLine("Hello World");

string result = stringBuilder.ToString();

The dotnet version of the StringBuilder is a all purpose version which normally fits a wide variety of needs. But sometimes low allocation is key. Therefore I created the ValueStringBuilder. It is not a class but a ref struct which tries to do as less allocations as possible. If you want to know how the ValueStringBuilder works and why it uses allocations and is even faster, checkout this blog post. The blog goes a bit more in detail how it works with a simplistic version of the ValueStringBuilder.

The library is not meant as a general replacement for the StringBuilder shipped with the .net framework itself. You can head over to the documentation and read about the "Known limitations". The library works best for a small to medium amount of strings (not multiple 100'000 characters, even though it can be still faster and uses less allocations). At anytime you can convert the ValueStringBuilder to a "normal" StringBuilder and vice versa.

The normal use case is to add concatenate strings in a hot-path where the goal is to put as minimal pressure on the GC as possible.

A more detailed documentation can be found here.

The following table gives you a small comparison between the StringBuilder which is part of .NET, ZString and the ValueStringBuilder:

|              Method |       Mean |    Error |    StdDev |     Median | Ratio | RatioSD |   Gen 0 |  Gen 1 | Allocated |
|-------------------- |-----------:|---------:|----------:|-----------:|------:|--------:|--------:|-------:|----------:|
| DotNetStringBuilder |   401.7 ns | 29.15 ns |  84.56 ns |   373.4 ns |  1.00 |    0.00 |  0.3576 |      - |   1,496 B |
|  ValueStringBuilder |   252.8 ns |  9.05 ns |  26.27 ns |   249.0 ns |  0.65 |    0.13 |  0.1583 |      - |     664 B |
|  ZStringBuilderUtf8 | 1,239.0 ns | 44.93 ns | 131.06 ns | 1,192.0 ns |  3.18 |    0.56 | 15.6250 |      - |  66,136 B |
| ZStringBuilderUtf16 | 1,187.6 ns | 21.35 ns |  25.42 ns | 1,185.0 ns |  2.88 |    0.52 | 15.6250 | 0.0019 |  66,136 B |

For more comparison check the documentation.

Another benchmark shows that this ValueStringBuilder uses less memory when it comes to appending ValueTypes such as int, double, ...

|              Method |     Mean |    Error |   StdDev |  Gen 0 | Allocated |
|-------------------- |---------:|---------:|---------:|-------:|----------:|
| DotNetStringBuilder | 17.21 us | 0.622 us | 1.805 us | 1.5259 |      6 KB |
|  ValueStringBuilder | 16.24 us | 0.496 us | 1.462 us | 0.3357 |      1 KB |

Checkout the Benchmark for more detailed comparison and setup.