Introduction to C#

What is C#?

C# (pronounced "C sharp") is a modern, object-oriented, and type-safe programming language developed by Microsoft as part of the .NET platform. It was designed by Anders Hejlsberg and released in 2000. C# is heavily influenced by Java and C++.

Key Features

• Strongly Typed — every variable has a declared type checked at compile time
• Object-Oriented — classes, interfaces, inheritance, polymorphism
• Cross-Platform — .NET runs on Windows, Linux, and macOS
• Modern Syntax — LINQ, async/await, records, pattern matching, nullable types
• Garbage Collected — no manual memory management needed

Your First C# Program

// Program.cs
using System;

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

Top-Level Statements (C# 9+)

// No class/Main boilerplate needed in C# 9+
Console.WriteLine("Hello, World!");

Compiling and Running

dotnet new console -n MyApp
cd MyApp
dotnet run

Where C# is Used

• 🎮 Game development with Unity (most popular game engine)
• 🌐 Web APIs and microservices with ASP.NET Core
• 🖥️ Desktop apps with WPF and WinForms
• 📱 Mobile apps with .NET MAUI / Xamarin
• ☁️ Cloud services on Azure