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Concatenate Lists in C#: net10.0, collection expression, parameterised benchmark #2278

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vladimir-pecanac-main merged 1 commit into from
Oct 11, 2026
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Concatenate Lists in C#: net10.0, collection expression, parameterised benchmark #2278

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4 changes: 2 additions & 2 deletions collections-lists/ConcatenateLists/BenchmarkRunner/BenchmarkRunner.csproj
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Original file line number Diff line number Diff line change
Expand Up @@ -2,13 +2,13 @@

<PropertyGroup>
<OutputType>Exe</OutputType>
<TargetFramework>net6.0</TargetFramework>
<TargetFramework>net10.0</TargetFramework>
<ImplicitUsings>enable</ImplicitUsings>
<Nullable>enable</Nullable>
</PropertyGroup>

<ItemGroup>
<PackageReference Include="BenchmarkDotNet" Version="0.13.1" />
<PackageReference Include="BenchmarkDotNet" Version="0.15.8" />
</ItemGroup>

<ItemGroup>
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36 changes: 32 additions & 4 deletions collections-lists/ConcatenateLists/BenchmarkRunner/ConcatenatorBenchmark.cs
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Expand Up @@ -9,14 +9,30 @@ namespace BenchmarkRunner
[Orderer(SummaryOrderPolicy.FastestToSlowest)]
public class ConcatenatorBenchmark
{
private readonly List<string> _firstList = Enumerable.Repeat("Code", 1_000_000).ToList();
private readonly List<string> _secondList = Enumerable.Repeat("Maze", 1_000_000).ToList();
[Params(50_000, 1_000_000)]
public int Size;

private List<string> _firstList = [];
private List<string> _secondList = [];
private readonly Concatenator _concatenator = new();


[GlobalSetup]
public void Setup()
{
_firstList = Enumerable.Range(0, Size).Select(i => $"Code{i}").ToList();
_secondList = Enumerable.Range(0, Size).Select(i => $"Maze{i}").ToList();
}

[Benchmark]
public void UsingAdd()
{
_concatenator.UsingAdd(_firstList, _secondList);
_concatenator.UsingAdd(_firstList, _secondList);
}

[Benchmark]
public void UsingAddNoCapacity()
{
_concatenator.UsingAddNoCapacity(_firstList, _secondList);
}

[Benchmark]
Expand All @@ -37,6 +53,12 @@ public void UsingAddRange()
_concatenator.UsingAddRange(_firstList, _secondList);
}

[Benchmark]
public void UsingAddRangeNoCapacity()
{
_concatenator.UsingAddRangeNoCapacity(_firstList, _secondList);
}

[Benchmark]
public void UsingCopyTo()
{
Expand All @@ -48,5 +70,11 @@ public void UsingSelectMany()
{
_concatenator.UsingSelectMany(_firstList, _secondList);
}

[Benchmark]
public void UsingCollectionExpression()
{
_concatenator.UsingCollectionExpression(_firstList, _secondList);
}
}
}
2 changes: 1 addition & 1 deletion collections-lists/ConcatenateLists/ConcatenateLists/ConcatenateLists.csproj
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Expand Up @@ -2,7 +2,7 @@

<PropertyGroup>
<OutputType>Exe</OutputType>
<TargetFramework>net6.0</TargetFramework>
<TargetFramework>net10.0</TargetFramework>
<ImplicitUsings>enable</ImplicitUsings>
<Nullable>enable</Nullable>
</PropertyGroup>
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48 changes: 41 additions & 7 deletions collections-lists/ConcatenateLists/ConcatenateLists/Concatenator.cs
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Expand Up @@ -4,7 +4,24 @@ public class Concatenator
{
public List<string> UsingAdd(List<string> firstList, List<string> secondList)
{
var result = new List<string>(firstList.Count() + secondList.Count());
var result = new List<string>(firstList.Count + secondList.Count);

foreach (var item in firstList)
{
result.Add(item);
}

foreach (var item in secondList)
{
result.Add(item);
}

return result;
}

public List<string> UsingAddNoCapacity(List<string> firstList, List<string> secondList)
{
var result = new List<string>();

foreach (var item in firstList)
{
Expand All @@ -31,7 +48,17 @@ public List<string> UsingEnumerableUnion(List<string> firstList, List<string> se

public List<string> UsingAddRange(List<string> firstList, List<string> secondList)
{
var result = new List<string>(firstList.Count() + secondList.Count());
var result = new List<string>(firstList.Count + secondList.Count);

result.AddRange(firstList);
result.AddRange(secondList);

return result;
}

public List<string> UsingAddRangeNoCapacity(List<string> firstList, List<string> secondList)
{
var result = new List<string>();

result.AddRange(firstList);
result.AddRange(secondList);
Expand All @@ -41,19 +68,26 @@ public List<string> UsingAddRange(List<string> firstList, List<string> secondLis

public List<string> UsingCopyTo(List<string> firstList, List<string> secondList)
{
var combinedList = new string[firstList.Count() + secondList.Count()];
var combinedArray = new string[firstList.Count + secondList.Count];

firstList.CopyTo(combinedList);
secondList.CopyTo(combinedList, firstList.Count());
firstList.CopyTo(combinedArray, 0);
secondList.CopyTo(combinedArray, firstList.Count);

return combinedList.ToList();
return combinedArray.ToList();
}

public List<string> UsingSelectMany(List<string> firstList, List<string> secondList)
{
{
var combinedArray = new[] { firstList, secondList }.SelectMany(x => x);

return combinedArray.ToList();
}

public List<string> UsingCollectionExpression(List<string> firstList, List<string> secondList)
{
List<string> result = [.. firstList, .. secondList];

return result;
}
}
}
64 changes: 30 additions & 34 deletions collections-lists/ConcatenateLists/ConcatenateLists/Program.cs
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@@ -1,46 +1,42 @@
namespace ConcatenateLists;
using ConcatenateLists;

public class Program
{
public static void Main()
{
Console.WriteLine("---------- Concatenate Lists in C# ----------");
Console.WriteLine("---------- Concatenate Lists in C# ----------");

var firstList = new List<string>() { "Code", "Maze", "Concatenate" };
var secondList = new List<string>() { "Lists", "in", "C#" };
var firstList = new List<string>() { "Code", "Maze", "Concatenate" };
var secondList = new List<string>() { "Lists", "in", "C#" };

var concatenator = new Concatenator();
var concatenator = new Concatenator();

Console.WriteLine();
Console.WriteLine("------ Concatenate lists using Add");
PrintOut(concatenator.UsingAdd(firstList, secondList));
Console.WriteLine();
Console.WriteLine("------ Concatenate lists using Add");
PrintOut(concatenator.UsingAdd(firstList, secondList));

Console.WriteLine();
Console.WriteLine("------ Concatenate using Enumerable.Concat");
PrintOut(concatenator.UsingEnumerableConcat(firstList, secondList));
Console.WriteLine();
Console.WriteLine("------ Concatenate using Enumerable.Concat");
PrintOut(concatenator.UsingEnumerableConcat(firstList, secondList));

Console.WriteLine();
Console.WriteLine("------ Concatenate using Enumerable.Union");
PrintOut(concatenator.UsingEnumerableUnion(firstList, secondList));
Console.WriteLine();
Console.WriteLine("------ Concatenate using Enumerable.Union");
PrintOut(concatenator.UsingEnumerableUnion(firstList, secondList));

Console.WriteLine();
Console.WriteLine("------ Concatenate using AddRange");
PrintOut(concatenator.UsingAddRange(firstList, secondList));
Console.WriteLine();
Console.WriteLine("------ Concatenate using AddRange");
PrintOut(concatenator.UsingAddRange(firstList, secondList));

Console.WriteLine();
Console.WriteLine("------ Concatenate using List CopyTo");
PrintOut(concatenator.UsingCopyTo(firstList, secondList));
Console.WriteLine();
Console.WriteLine("------ Concatenate using List CopyTo");
PrintOut(concatenator.UsingCopyTo(firstList, secondList));

Console.WriteLine();
Console.WriteLine("------ Concatenate using SelectMany");
PrintOut(concatenator.UsingSelectMany(firstList, secondList));
Console.WriteLine();
Console.WriteLine("------ Concatenate using SelectMany");
PrintOut(concatenator.UsingSelectMany(firstList, secondList));

Console.ReadLine();
}
Console.WriteLine();
Console.WriteLine("------ Concatenate using a collection expression");
PrintOut(concatenator.UsingCollectionExpression(firstList, secondList));

private static void PrintOut(List<string> list)
{
list.ForEach(x => Console.Write($" => {x}"));
Console.WriteLine();
}
static void PrintOut(List<string> list)
{
list.ForEach(x => Console.Write($" => {x}"));
Console.WriteLine();
}
49 changes: 42 additions & 7 deletions collections-lists/ConcatenateLists/Tests/Tests.cs
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Expand Up @@ -15,7 +15,16 @@ public void GivenTwoLists_WhenUsingAddMethod_ThenReturnANewConcatenatedList()
{
var result = _concatenator.UsingAdd(_firstList, _secondList);

Assert.Equal(_expectedList.Count(), result.Count);
Assert.Equal(_expectedList.Count, result.Count);
Assert.Equal(_expectedList, result);
}

[Fact]
public void GivenTwoLists_WhenUsingAddNoCapacityMethod_ThenReturnANewConcatenatedList()
{
var result = _concatenator.UsingAddNoCapacity(_firstList, _secondList);

Assert.Equal(_expectedList.Count, result.Count);
Assert.Equal(_expectedList, result);
}

Expand All @@ -24,7 +33,7 @@ public void GivenTwoLists_WhenUsingEnumerableConcatMethod_ThenReturnANewConcaten
{
var result = _concatenator.UsingEnumerableConcat(_firstList, _secondList);

Assert.Equal(_expectedList.Count(), result.Count);
Assert.Equal(_expectedList.Count, result.Count);
Assert.Equal(_expectedList, result);
}

Expand All @@ -33,7 +42,7 @@ public void GivenTwoLists_WhenUsingEnumerableUnionMethod_ThenReturnANewConcatena
{
var result = _concatenator.UsingEnumerableUnion(_firstList, _secondList);

Assert.Equal(_expectedList.Count(), result.Count);
Assert.Equal(_expectedList.Count, result.Count);
Assert.Equal(_expectedList, result);
}

Expand All @@ -42,7 +51,16 @@ public void GivenTwoLists_WhenUsingAddRangeMethod_ThenReturnANewConcatenatedList
{
var result = _concatenator.UsingAddRange(_firstList, _secondList);

Assert.Equal(_expectedList.Count(), result.Count);
Assert.Equal(_expectedList.Count, result.Count);
Assert.Equal(_expectedList, result);
}

[Fact]
public void GivenTwoLists_WhenUsingAddRangeNoCapacityMethod_ThenReturnANewConcatenatedList()
{
var result = _concatenator.UsingAddRangeNoCapacity(_firstList, _secondList);

Assert.Equal(_expectedList.Count, result.Count);
Assert.Equal(_expectedList, result);
}

Expand All @@ -51,7 +69,7 @@ public void GivenTwoLists_WhenUsingCopyToMethod_ThenReturnANewConcatenatedList()
{
var result = _concatenator.UsingCopyTo(_firstList, _secondList);

Assert.Equal(_expectedList.Count(), result.Count);
Assert.Equal(_expectedList.Count, result.Count);
Assert.Equal(_expectedList, result);
}

Expand All @@ -60,8 +78,25 @@ public void GivenTwoLists_WhenUsingSelectManyMethod_ThenReturnANewConcatenatedLi
{
var result = _concatenator.UsingSelectMany(_firstList, _secondList);

Assert.Equal(_expectedList.Count(), result.Count);
Assert.Equal(_expectedList.Count, result.Count);
Assert.Equal(_expectedList, result);
}

[Fact]
public void GivenTwoLists_WhenUsingCollectionExpression_ThenReturnANewConcatenatedList()
{
var result = _concatenator.UsingCollectionExpression(_firstList, _secondList);

Assert.Equal(_expectedList.Count, result.Count);
Assert.Equal(_expectedList, result);
}

[Fact]
public void GivenListsWithDuplicates_WhenUsingEnumerableUnionMethod_ThenReturnEachValueOnce()
{
var result = _concatenator.UsingEnumerableUnion(new List<string> { "a", "a" }, new List<string> { "a" });

Assert.Equal(new List<string> { "a" }, result);
}
}
}
}
10 changes: 5 additions & 5 deletions collections-lists/ConcatenateLists/Tests/Tests.csproj
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@@ -1,21 +1,21 @@
<Project Sdk="Microsoft.NET.Sdk">

<PropertyGroup>
<TargetFramework>net6.0</TargetFramework>
<TargetFramework>net10.0</TargetFramework>
<ImplicitUsings>enable</ImplicitUsings>
<Nullable>enable</Nullable>

<IsPackable>false</IsPackable>
</PropertyGroup>

<ItemGroup>
<PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.1.0" />
<PackageReference Include="xunit" Version="2.4.1" />
<PackageReference Include="xunit.runner.visualstudio" Version="2.4.3">
<PackageReference Include="Microsoft.NET.Test.Sdk" Version="18.10.1" />
<PackageReference Include="xunit" Version="2.9.3" />
<PackageReference Include="xunit.runner.visualstudio" Version="4.0.1">
<IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
<PrivateAssets>all</PrivateAssets>
</PackageReference>
<PackageReference Include="coverlet.collector" Version="3.1.2">
<PackageReference Include="coverlet.collector" Version="10.1.0">
<IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
<PrivateAssets>all</PrivateAssets>
</PackageReference>
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