How to Create a Class Library in .NET Core

DevSniper
Published : 02 December 2024

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A class library is a project that contains reusable code such as functions, methods, and classes that can be shared across multiple applications. Class libraries encapsulate logic, making your codebase modular, maintainable and easier to test. In this article, we will explore how to create class library in .NET core application. After reading this article, you will be able to create class library easily.

Why should we use a Class Library

Code Reusability: Code Reusability: You can share the same logic across different projects without rewriting code
Maintainability: Changing in library will automatically reflect in all dependent projects
Separation of Concerns: It allows you to keep your application components organized.

Prerequisites

Before you start, ensure you have the following:

.NET SDK installed Download here
Visual Studio OR Visual Studio Code
Basic knowledge of C# and .NET Core

Method 1 : Using the .NET CLI

Step 1: Create the Class Library Project

Open a terminal or command prompt
Navigate to the directory/folder where you want to create the project.
Run the following command to create a new class library
```
dotnet new classlib -n <LibraryName>
```
This will generate a project folder named <LibraryName> with necessary files including: <LibraryName>.csproj (project file) and a default class file (Class1.cs).

Step 2: Navigate into the Project Directory

cd <LibraryName>

Step 3: Build the Class Library

dotnet build

This command compiles the project and generates a .dll file in the bin directory. The .dll file is the compiled library that you can reference in other projects

Step 4: Reference the Class Library in Another Project

Navigate to the directory of the project/application that will use this library

Add the reference of class library

dotnet add reference ../<LibraryName>/<LibraryName>.csproj

Run the build command in the main project directory to ensure the reference is correctly added
```
dotnet build
```

Method 2: Using Visual Studio

Create a New Class Library Project

Open Visual Studio
Click on "Create a new project"
Select "Class Library" and click Next.
Provide a name for your class library and click Create.