SliceToMultiple-SpanVsSubString

SliceToMultiple-SpanVsSubString

using BenchmarkDotNet.Attributes;
using System;
using System.Collections.Generic;

namespace Benchmark_ToListCall
{
    [MemoryDiagnoser]
    public class StringBenchmarks2
    {
        private string stringToSlice;

        [GlobalSetup]
        public void Init()
        {
            this.stringToSlice = "Lorem ipsum dolor sit amet";
        }

        [Benchmark]
        public List<string> WithSpan()
        {
            return SliceToMultipleSpan(this.stringToSlice, 3);
        }

        [Benchmark]
        public List<string> WithoutSpan()
        {
            return SliceToMultiple(this.stringToSlice, 3);
        }

        List<string> SliceToMultiple(string value, int sliceLength)
        {
            if (value == null)
            {
                value = string.Empty;
            }

            var resultList = new List<string>(value.Length / sliceLength);
            var startIndexToSliceFrom = 0;
            var totalLengthSliced = 0;

            while (totalLengthSliced < value.Length)
            {
                var lengthToSlice = Math.Min(sliceLength, value.Length - totalLengthSliced);

                resultList.Add(value.Substring(startIndexToSliceFrom, lengthToSlice));

                totalLengthSliced = totalLengthSliced + lengthToSlice;
                startIndexToSliceFrom = totalLengthSliced;
            }

            return resultList;
        }

        List<string> SliceToMultipleSpan(string value, int sliceLength)
        {
            if (value == null)
            {
                value = string.Empty;
            }

            var resultList = new List<string>(value.Length / sliceLength);
            var startIndexToSliceFrom = 0;
            var totalLengthSliced = 0;
            var valueSpan = value.AsSpan();

            while (totalLengthSliced < value.Length)
            {
                var lengthToSlice = Math.Min(sliceLength, value.Length - totalLengthSliced);

                resultList.Add(valueSpan.Slice(startIndexToSliceFrom, lengthToSlice).ToString());

                totalLengthSliced = totalLengthSliced + lengthToSlice;
                startIndexToSliceFrom = totalLengthSliced;
            }

            return resultList;
        }

    }
}

SliceToMultiple-SpanVsSubString-Results

``` ini

BenchmarkDotNet=v0.12.1, OS=Windows 10.0.21340
Intel Xeon CPU E5-1650 v4 3.60GHz, 1 CPU, 12 logical and 6 physical cores
.NET Core SDK=5.0.201
  [Host]     : .NET Core 3.1.13 (CoreCLR 4.700.21.11102, CoreFX 4.700.21.11602), X64 RyuJIT
  DefaultJob : .NET Core 3.1.13 (CoreCLR 4.700.21.11102, CoreFX 4.700.21.11602), X64 RyuJIT


```
|      Method |     Mean |   Error |  StdDev |  Gen 0 |  Gen 1 | Gen 2 | Allocated |
|------------ |---------:|--------:|--------:|-------:|-------:|------:|----------:|
|    WithSpan | 203.8 ns | 4.10 ns | 6.00 ns | 0.0713 | 0.0002 |     - |     560 B |
| WithoutSpan | 203.9 ns | 4.14 ns | 8.46 ns | 0.0713 | 0.0002 |     - |     560 B |