A class library in .NET is a collection of reusable classes and methods that can be used by other applications or projects. Creating a class library project using the .NET Command Line Interface (CLI) is a straightforward process. This guide will walk you through the steps to create a new class library project using the CLI.

What is a Class Library?

A class library is a project that contains code that can be shared across multiple applications. It typically includes classes, interfaces, and methods that encapsulate specific functionality. Class libraries are compiled into a .dll (Dynamic Link Library) file, which can be referenced by other projects.

How to Create a New Class Library Project

To create a new class library project using the CLI, follow these steps:

Step 1: Open Your Command Line Interface

Open your terminal (macOS/Linux) or command prompt (Windows).

Step 2: Navigate to the Desired Directory

Navigate to the directory where you want to create your new class library project. You can use the cd command to change directories:

cd /path/to/your/directory

Step 3: Run the dotnet new Command

Use the following command to create a new class library project:

dotnet new classlib -n MyClassLibrary

In this command, replace MyClassLibrary with the desired name for your class library project. The classlib template is used to create a new class library.

Example

Suppose you want to create a new class library named Utilities. You would do the following:

cd /path/to/your/directory
dotnet new classlib -n Utilities

After executing this command, you will see output indicating that the class library has been created successfully. You will find a new folder named Utilities containing the project files.

Project Structure

The newly created class library project will have the following structure:

Utilities/
    ├── Utilities.csproj
    └── Class1.cs

- Utilities.csproj: This is the project file that contains information about the project, including its dependencies and configuration.
- Class1.cs: This is a default class file created with the project. You can rename it and add your own classes as needed.

Building the Class Library

To build your class library project, navigate to the project directory and run the following command:

cd Utilities
dotnet build

This command compiles the project and generates the .dll file in the bin directory.

Conclusion

Creating a new class library project using the CLI is a simple and efficient process. By following the steps outlined in this guide, you can easily set up a class library that can be reused across multiple applications. Understanding how to create and manage class libraries is essential for any .NET developer looking to build modular and maintainable applications.