BenchmarkDotNet: DOTNET Lab & Demo

AllocationBenchmarks.cs

using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Order;
using System;
using System.Text;

namespace BenchmarkDotNetLab
{
    [MemoryDiagnoser]
    [Orderer(SummaryOrderPolicy.FastestToSlowest)]
    [RankColumn]
    public class AllocationBenchmarks
    {
        [Params(100, 1000)]
        public int N;

        // Bad: repeatedly concatenating strings in a loop
        [Benchmark(Baseline = true)]
        public string StringConcat_PlusOperator()
        {
            string result = string.Empty;

            for (int i = 0; i < N; i++)
            {
                result += "Item" + i; // each concat allocates
            }

            return result;
        }

        // Better: use StringBuilder
        [Benchmark]
        public string StringConcat_StringBuilder()
        {
            var sb = new StringBuilder();

            for (int i = 0; i < N; i++)
            {
                sb.Append("Item");
                sb.Append(i);
            }

            return sb.ToString();
        }
    }
}