C# Programming Tutorial: From Fundamentals to Advanced Application Development

📘 Chapter 1: Introduction to C# and .NET

🧠 What is C#?

C# (pronounced C-Sharp) is a modern, object-oriented, type-safe programming language developed by Microsoft in 2000 as part of its .NET initiative. It was designed by Anders Hejlsberg, the same person who worked on Turbo Pascal and Delphi.

C# combines the high-level productivity of languages like Java with low-level control capabilities akin to C++, making it a versatile and powerful tool for developers across industries.

🧩 What is .NET?

.NET is an open-source, cross-platform framework created by Microsoft that supports the development and execution of applications for web, mobile, desktop, IoT, gaming, cloud, and more.

✳️ .NET Includes:

• CLR (Common Language Runtime) – Executes and manages code
• Base Class Library (BCL) – Predefined classes, functions, types
• Language Support – C#, F#, VB.NET
• ASP.NET Core – Web development framework
• Entity Framework – Database ORM

🧱 Structure of a C# Program

Here’s a basic "Hello, World!" program in C#:

using System;

class Program

{

    static void Main(string[] args)

    {

        Console.WriteLine("Hello, World!");

    }

}

🔍 Breakdown of the Code:

🚀 Features of C# Language

💡 Why Use C#?

• Powerful, fast, and modern
• Backed by Microsoft and a massive community
• Fully integrated with Visual Studio and .NET
• Works cross-platform via .NET Core
• Perfect for enterprise software and startups alike

🛠️ Setting Up the Environment

🔹 Option 1: Visual Studio (Recommended)

• Download from visualstudio.microsoft.com
• Install the “.NET desktop development” workload
• Start a new Console App (.NET Core) project

🔹 Option 2: Visual Studio Code + .NET CLI

Install:

• .NET SDK
• VS Code
• C# extension for VS Code

✅ Create First Project with CLI

dotnet new console -n MyApp

cd MyApp

dotnet run

📘 Compilation and Execution in C#

C# code is compiled into Intermediate Language (IL), then executed by the CLR. This allows cross-platform compatibility, runtime optimization, and security.

🧭 Compilation Workflow

C# Source Code (.cs)

      ↓

C# Compiler (csc)

      ↓

Intermediate Language (IL)

      ↓

Common Language Runtime (CLR)

      ↓

Native Machine Code

🧰 Namespaces in C#

Namespaces organize code and prevent naming conflicts.

namespace MyApp {

    class Program {

        static void Main(string[] args) {

            Console.WriteLine("Hi from MyApp");

        }

    }

}

You can use namespaces like:

using MyApp;

📦 Overview of the .NET Ecosystem

🧪 Sample Program: Basic Calculator

using System;

class Calculator

{

    static void Main()

    {

        int a = 10, b = 5;

        Console.WriteLine("Sum: " + (a + b));

        Console.WriteLine("Product: " + (a * b));

    }

}

Output:

Sum: 15

Product: 50

🎯 C# vs Other Languages

📚 What You'll Learn in Later Chapters

• Variables, data types, operators
• Control structures (if, loops)
• Classes, objects, and OOP principles
• Exception handling
• File I/O and databases
• Building real-world applications

✅ Summary Table