C# in Action - Building Robust and Scalable Applications

📘 Table of Contents

• 1. Introduction to C#
• 2. Setting Up Environment
• 3. Basic Syntax
• 4. Variables and Data Types
• 5. Conditionals and Loops
• 6. Methods
• 7. Object-Oriented Programming
• 8. Best Practices
• 9. Mini Project
• 10. Conclusion

1. Introduction to C#

C# (pronounced “C-sharp”) is a modern, object-oriented language developed by Microsoft. It’s widely used for desktop applications, web apps, and game development with Unity.

2. Setting Up Environment

To write and run C# programs, install:

• Visual Studio or Visual Studio Code
• .NET SDK from dotnet.microsoft.com

using System;

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

3. Basic Syntax

Each C# program starts with a Main() method.

4. Variables and Data Types

int age = 25;
string name = "Alice";
double price = 9.99;
bool isOnline = true;

5. Conditionals and Loops

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

if (age > 18) {
  Console.WriteLine("Adult");
}

6. Methods

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

7. Object-Oriented Programming

class Person {
  public string Name;
  public void Greet() {
    Console.WriteLine($"Hello, {Name}!");
  }
}

class Program {
  static void Main() {
    Person p = new Person();
    p.Name = "John";
    p.Greet();
  }
}

8. Best Practices

• Follow PascalCase for class names and methods.
• Use meaningful variable names.
• Keep methods short and focused.

9. Mini Project — Simple Calculator

using System;

class Calculator {
  static void Main() {
    Console.Write("Enter first number: ");
    double a = Convert.ToDouble(Console.ReadLine());
    Console.Write("Enter operator (+, -, *, /): ");
    char op = Console.ReadLine()[0];
    Console.Write("Enter second number: ");
    double b = Convert.ToDouble(Console.ReadLine());

    double result = 0;
    switch(op) {
      case '+': result = a + b; break;
      case '-': result = a - b; break;
      case '*': result = a * b; break;
      case '/': result = a / b; break;
      default: Console.WriteLine("Invalid operator."); return;
    }

    Console.WriteLine($"Result: {result}");
  }
}

10. Conclusion

C# is powerful, elegant, and versatile — ideal for building secure and scalable applications across platforms.