String concat vs StringBuilder

string-concat-vs-stringbuilder.cs

#LINQPad optimize+
void Main()
{
	
	
	var summary = BenchmarkRunner.Run<StringConcatenationPerformance>();
}

[MemoryDiagnoser]

public class StringConcatenationPerformance
{

	[Params(2, 4, 6, 8, 10, 12, 14, 16, 18, 20)]
	public int StringsCount;

	public string[] items;

	[Benchmark]
	public void UseAppend()
	{
		items = Enumerable.Range(0, StringsCount).Select(_ => _.ToString()).ToArray();

		string value = "";

		foreach (var item in items)
		{
			value += item;
		}
	}

	[Benchmark]
	public void UseConcat()
	{
		items = Enumerable.Range(0, StringsCount).Select(_ => _.ToString()).ToArray();
		string value = "";

		foreach (var item in items)
		{
			value = string.Concat(value, item);
		}

	}

	[Benchmark]
	public void UseStringBuilder()
	{
		items = Enumerable.Range(0, StringsCount).Select(_ => _.ToString()).ToArray();
		string value = "";
		StringBuilder sb = new StringBuilder();

		foreach (var item in items)
		{
			sb.Append(item);
		}
		value = sb.ToString();

	}
}