Master C#: The Complete Beginner’s Guide

C# is a modern, object-oriented programming language developed by Microsoft. It’s part of the .NET ecosystem and is used for building desktop apps, games (Unity), APIs, enterprise software, and mobile apps.

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Why Learn C#?

• Easy syntax (similar to Java & C++).
• Cross-platform with .NET Core/.NET 6+.
• Widely used in game development (Unity).
• Powerful for web apps via ASP.NET.

Hello World

using System;

class Program {
    static void Main() {
        Console.WriteLine("Hello, C#!");
    }
}

Variables & Data Types

int age = 25;
double pi = 3.14;
char grade = 'A';
string name = "Alice";
bool isStudent = true;

Input & Output

Console.Write("Enter your name: ");
string name = Console.ReadLine();
Console.WriteLine("Hello " + name);

Operators

• Arithmetic: +, -, *, /, %
• Comparison: ==, !=, <, >, <=, >=
• Logical: && (AND), || (OR), ! (NOT)

Conditionals

int age = 20;
if (age >= 18) {
    Console.WriteLine("Adult");
} else {
    Console.WriteLine("Minor");
}

Loops

// For loop
for (int i = 1; i <= 5; i++) {
    Console.WriteLine(i);
}

// While loop
int x = 0;
while (x < 3) {
    Console.WriteLine(x);
    x++;
}

Functions

static int Add(int a, int b) {
    return a + b;
}

static void Main() {
    Console.WriteLine(Add(3, 4));
}

Arrays & Lists

// Array
int[] numbers = {1, 2, 3};

// List
using System.Collections.Generic;
List<string> fruits = new List<string>() {"Apple", "Banana"};
fruits.Add("Cherry");

Strings

string name = "Alice";
Console.WriteLine("Length: " + name.Length);
Console.WriteLine("First letter: " + name[0]);

Object-Oriented Programming (OOP)

class Person {
    public string Name;
    public int Age;

    public void Greet() {
        Console.WriteLine("Hi, I'm " + Name);
    }
}

class Program {
    static void Main() {
        Person p1 = new Person();
        p1.Name = "Alice";
        p1.Age = 25;
        p1.Greet();
    }
}

Properties & Encapsulation

class Person {
    private string name;

    public string Name {
        get { return name; }
        set { name = value; }
    }
}

class Program {
    static void Main() {
        Person p = new Person();
        p.Name = "Alice";
        Console.WriteLine(p.Name);
    }
}

File Handling

using System.IO;

class Program {
    static void Main() {
        File.WriteAllText("data.txt", "Hello, File!");
        string content = File.ReadAllText("data.txt");
        Console.WriteLine(content);
    }
}

Mini Project: Simple Calculator

using System;

class Calculator {
    static int Add(int a, int b) => a + b;
    static int Sub(int a, int b) => a - b;
    static int Mul(int a, int b) => a * b;
    static double Div(int a, int b) => (double)a / b;

    static void Main() {
        Console.WriteLine(Add(5, 3));
        Console.WriteLine(Sub(10, 4));
        Console.WriteLine(Mul(2, 6));
        Console.WriteLine(Div(8, 2));
    }
}

Popular Frameworks & Uses

• ASP.NET → Web development
• Unity → Game development
• Xamarin / .NET MAUI → Mobile apps
• WPF / WinForms → Desktop apps

Best Practices

• Follow .NET naming conventions (PascalCase for methods/classes).
• Use var for type inference when clear.
• Prefer properties over public fields.
• Use exception handling with try/catch.

Next Steps

1. Learn OOP deeply (inheritance, polymorphism, interfaces).
2. Explore async programming with async/await.
3. Build small apps (to-do list, calculator, CRUD app).
4. Explore Unity for games or ASP.NET for web APIs.

Conclusion

C# is a modern, versatile, and powerful language for beginners and pros alike. Whether you want to build games, enterprise apps, or web APIs, C# and the .NET ecosystem have you covered. 🚀