C# Creating a Class Library

This instruction post is an abbreviation of Microsoft tutorial found HERE.

Contents

Create the Library

Using the Library

Unit Testing

Including the .dss Directly

Setup

Create an SLN (project solution file)

An SLN is a Visual Studio solution file that keeps information about the organization of projects in a file.

dotnet new sln

Create the class library project

The -o (–output) flag specifies the directory to place the project. It will create the directory.

dotnet new classlib -o StringLibrary

Add the project to the solution

dotnet sln add StringLibrary/StringLibrary.csproj

Add code to the library

Add the following code to the StringLibrary/Class1.cs file

namespace UtilityLibraries;

public static class StringLibrary
{
    public static bool StartsWithUpper(this string? str)
    {
        if (string.IsNullOrWhiteSpace(str))
            return false;

        char ch = str[0];
        return char.IsUpper(ch);
    }
}

Build the solution

dotnet build

Using the Library

Create a console app

dotnet new console -o ShowCase

Add the console app to the solution

dotnet sln add ShowCase/ShowCase.csproj

Modify the ShowCase/Program.cs file

using UtilityLibraries;

class Program {
    static void Main(string[] args) {
        foreach(string s in args){
            var uc = s.StartsWithUpper();
            Console.WriteLine($"String {s} starts with uppser case {uc}");
        }
    }
}

Add a ‘StringLibrary’ reference to ‘ShowCase’

dotnet add ShowCase/ShowCase.csproj reference StringLibrary/StringLibrary.csproj

Run ‘ShowCase’

dotnet run --project ShowCase/ShowCase.csproj AB ab

Unit Testing

Create the unit test project and add a reference

dotnet new mstest -o StringLibraryTest
dotnet add StringLibraryTest/StringLibraryTest.csproj reference StringLibrary/StringLibrary.csproj

Run the unit test

dotnet test StringLibraryTest/StringLibraryTest.csproj

Including the .dll directly

Add the following to your project’s .csproj file. Change the StringLibrary project name as necessary.

  <ItemGroup>
    <Reference Include="StringLibrary">
      <HintPath>./lib/StringLibrary.dll</HintPath>
    </Reference>
  </ItemGroup>

Tags: C#dotnetlibrary