.NET Documentation

Core Concepts of .NET

Welcome to the foundational concepts of the .NET ecosystem. This guide will walk you through the essential building blocks that make .NET a powerful and versatile platform for building modern applications.

What is .NET?

.NET is a free, cross-platform, open-source developer platform for building many different types of applications. With .NET, you can:

• Build web, desktop, mobile, game, IoT, and cloud applications.
• Use C#, F#, or Visual Basic to write code.
• Target Windows, macOS, Linux, Android, iOS, and many other operating systems.

It consists of several key components that work together to provide a rich development experience.

Core Components

Common Language Runtime (CLR)

The CLR is the execution engine of .NET. It provides essential services such as:

• Memory Management: Automatic garbage collection to reclaim memory.
• Type Safety: Ensures that code runs correctly and doesn't access invalid memory.
• Exception Handling: Manages runtime errors gracefully.
• Just-In-Time (JIT) Compilation: Compiles intermediate language (IL) code into native machine code at runtime for optimal performance.

All .NET languages compile to a common intermediate language (IL), which the CLR then executes. This enables interoperability between different .NET languages.

C# (C Sharp)

C# is a modern, object-oriented programming language developed by Microsoft. It's the most popular language for .NET development due to its:

• Type Safety: Strongly typed, reducing runtime errors.
• Productivity: Rich syntax and features like LINQ, async/await, and pattern matching.
• Versatility: Suitable for a wide range of application types.

Here's a simple C# example:

using System;

public class Greeter
{
    public static void Main(string[] args)
    {
        // Prompt the user for their name
        Console.Write("Enter your name: ");
        string? name = Console.ReadLine();

        // Greet the user
        string message = $"Hello, {name ?? "Guest"}!";
        Console.WriteLine(message);
    }
}
            

Base Class Library (BCL)

The BCL is a comprehensive set of reusable, object-oriented types and classes that provide common functionality. It includes:

• Data Structures: Collections like lists, dictionaries, and arrays.
• I/O Operations: File system access, network communication.
• String Manipulation: Powerful text processing capabilities.
• Networking: Support for HTTP, TCP, and other protocols.
• Security: Cryptography and authentication features.
• Data Access: Libraries for interacting with databases (e.g., ADO.NET, Entity Framework Core).

The BCL is a crucial part of the .NET SDK and is accessible from any .NET language.

Software Development Kit (SDK) & Tools

The .NET SDK includes everything you need to develop .NET applications:

• Compilers: C#, F#, Visual Basic compilers.
• Runtime: The .NET runtime (e.g., .NET 8, .NET 7).
• Core Libraries: The BCL.
• Command-Line Interface (CLI): The dotnet CLI is a powerful tool for creating, building, testing, and publishing .NET applications.

Key dotnet CLI commands:

• dotnet new: Creates a new project.
• dotnet build: Compiles the project.
• dotnet run: Runs the project.
• dotnet test: Runs tests.
• dotnet publish: Creates a deployable artifact.

Key Features of Modern .NET

• Cross-Platform: Run your applications on Windows, macOS, and Linux without modification.
• High Performance: .NET is designed for speed and efficiency, rivaling native code.
• Open Source & Community Driven: Developed openly on GitHub with active community involvement.
• Unified Platform: .NET 5 and later versions unify .NET Core and .NET Framework into a single, consistent platform.
• Modern Language Features: Continually updated with powerful C# language features.
• Cloud-Native: Optimized for microservices, containers (Docker), and cloud deployment (Azure, AWS, GCP).

Types of Applications You Can Build

.NET empowers you to build a diverse range of applications:

• Web Applications: ASP.NET Core for high-performance, cross-platform web apps, APIs, and microservices.
• Desktop Applications: WPF, Windows Forms for Windows desktop apps, and .NET MAUI for cross-platform native UI (Windows, macOS, iOS, Android).
• Mobile Applications: .NET MAUI provides a single codebase for iOS and Android apps.
• Cloud-Native Applications: Services, microservices, serverless functions.
• Games: Using engines like Unity.
• IoT Applications: For embedded devices.
• Machine Learning & AI: With ML.NET and integration with other AI frameworks.

Explore the different sections of MSDN to dive deeper into each of these areas!