Bits of .NET

Timing code with DateTime.Now is inaccurate. BenchmarkDotNet runs proper benchmarks with statistical analysis.

Install:

dotnet add package BenchmarkDotNet

Create Benchmark:

using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Running;

[MemoryDiagnoser]
public class StringBenchmarks
{
    [Benchmark]
    public string StringConcat()
    {
        string result = "";
        for (int i = 0; i < 1000; i++)
            result += i.ToString();
        return result;
    }

    [Benchmark]
    public string StringBuilder()
    {
        var sb = new System.Text.StringBuilder();
        for (int i = 0; i < 1000; i++)
            sb.Append(i);
        return sb.ToString();
    }
}

// Run benchmarks
BenchmarkRunner.Run();

Output:

|        Method |      Mean |  Allocated |
|-------------- |----------:|-----------:|
| StringConcat  | 183.2 μs  |  2.01 MB   |
| StringBuilder |  15.3 μs  |  20.5 KB   |

StringBuilder is 12x faster with 100x less allocation!

Attributes: [Benchmark], [MemoryDiagnoser], [Params(…)], [GlobalSetup]