.NET Fundamentals

Welcome to the fundamental concepts of the .NET ecosystem. This section will guide you through the core components and ideas that make .NET a powerful and versatile platform for building various applications.

What is .NET?

.NET is a free, cross-platform, open-source framework for building many different types of applications. With .NET, you can create traditional Windows desktop applications, connect cloud services, build high-performance web applications, and much more. .NET supports multiple programming languages, with C# being the most popular.

Key features of .NET include:

• Cross-Platform: Run your applications on Windows, macOS, and Linux.
• Open-Source: Developed and maintained by Microsoft and the community.
• High Performance: Optimized for speed and efficiency.
• Unified Platform: A single .NET runtime and Base Class Library (BCL) for all .NET applications.

Core Concepts

Understanding these core concepts is crucial for developing with .NET:

• Common Language Runtime (CLR): The runtime environment that manages the execution of .NET programs. It provides services like memory management (garbage collection), exception handling, and security.
• Base Class Library (BCL): A comprehensive set of reusable types and classes that provide common functionality, such as file I/O, networking, and data structures.
• Intermediate Language (IL): Code written in .NET languages (like C#) is compiled into IL, a platform-agnostic intermediate representation. The CLR then compiles IL into native machine code just-in-time (JIT) for execution.
• Managed Code: Code that is executed by the CLR. This means it benefits from the CLR's services.

Hello, World!

Let's start with a simple "Hello, World!" application. This is a classic first step in learning any programming language.

using System;

public class HelloWorld
{
    public static void Main(string[] args)
    {
        Console.WriteLine("Hello, World!");
    }
}
            

This program defines a class `HelloWorld` with a `Main` method, which is the entry point for execution. The `Console.WriteLine` method outputs the string to the console.

Language Fundamentals

.NET supports several programming languages, but C# is the most widely used. Here are some fundamental C# concepts:

• Data Types: C# is a strongly-typed language. Common data types include `int` (integers), `string` (text), `bool` (true/false), and `double` (floating-point numbers).
• Variables: Used to store data. You declare a variable by specifying its type and name: int count = 10;
• Control Flow: Directs the execution path of your program. Key constructs include:
  • if/else statements
  • for, while, do-while loops
  • switch statements
• Object-Oriented Programming (OOP): C# is an object-oriented language. Concepts like classes, objects, inheritance, polymorphism, and encapsulation are fundamental.

Runtime

The .NET Runtime (formerly .NET Framework Runtime and .NET Core Runtime) is the heart of the .NET platform. It provides the essential services needed to run .NET applications.

• Common Language Runtime (CLR): Manages code execution, memory, and threading.
• Just-In-Time (JIT) Compilation: Compiles IL code into native machine code at runtime, optimizing performance.
• Garbage Collection (GC): Automatically manages memory by reclaiming memory that is no longer in use by the application.
• Exception Handling: Provides a structured way to handle runtime errors gracefully.

SDK

The .NET Software Development Kit (SDK) contains everything you need to develop .NET applications. It includes:

• The .NET Runtime: For running .NET applications.
• The .NET CLI: A command-line interface for creating, building, running, and publishing .NET applications.
• Compilers: C# compiler (csc.exe) and F# compiler (fsc.exe).
• Build Tools: MSBuild for project compilation and management.

You can download the .NET SDK from the official .NET website.

CLI

The .NET Command-Line Interface (CLI) is a cross-platform tool that allows you to interact with the .NET ecosystem from your terminal.

Some common .NET CLI commands:

Command	Description
dotnet new console	Creates a new console application project.
dotnet build	Builds the project and its dependencies.
dotnet run	Compiles and runs the project.
dotnet publish	Publishes the application for deployment.
dotnet --version	Displays the installed .NET SDK version.

Continue exploring the documentation to dive deeper into specific areas like web development, desktop applications, or cloud services.