Introduction to Programming in C#

C# (pronounced “C Sharp”) is a modern, object-oriented programming language developed by Microsoft. It is widely used for building Windows applications, web applications, games (via Unity), and more. C# is part of the .NET ecosystem, which provides a rich set of libraries and tools for developers. Its simplicity, versatility, and strong typing make it a great choice for both beginners and experienced programmers.

This guide will introduce you to the fundamentals of C# programming, helping you write clean, efficient, and maintainable code.

Table of Contents

1. What is C#?
2. Setting Up Your Environment
3. Variables and Data Types
4. Control Flow
5. Functions
6. Arrays and Collections
7. Object-Oriented Programming
8. Exception Handling
9. LINQ
10. Asynchronous Programming

What is C#?

C# is a general-purpose, object-oriented programming language designed for the .NET platform. It is used for building a wide range of applications, from desktop to web and mobile.

// Example: Your first C# program
using System;

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

Setting Up Your Environment

To write and run C# programs, you need the .NET SDK installed on your system. You can download it from the official .NET website.

# Example: Running a C# program
dotnet run

Variables and Data Types

C# is statically typed, meaning variable types are determined at compile time. Common data types include int, float, double, string, and bool.

// Example: Declaring variables
using System;

class Program
{
    static void Main()
    {
        int age = 25;
        double height = 5.9;
        string name = "Alice";
        bool isStudent = true;

        Console.WriteLine($"Name: {name}, Age: {age}, Height: {height}");
    }
}

Control Flow

C# supports if, else, switch, and loops (for, while, do-while) for controlling program flow.

// Example: Conditional statement
using System;

class Program
{
    static void Main()
    {
        int age = 18;

        if (age >= 18)
        {
            Console.WriteLine("You are an adult.");
        }
        else
        {
            Console.WriteLine("You are a minor.");
        }
    }
}

Functions

Functions (or methods) are defined using the void or return_type keyword. C# supports both static and instance methods.

// Example: Function
using System;

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

    static void Main()
    {
        int result = Add(5, 10);
        Console.WriteLine($"Result: {result}"); // 15
    }
}

Arrays and Collections

C# provides arrays and collections like List, Dictionary, and HashSet for storing and manipulating data.

// Example: List
using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        List<int> numbers = new List<int> { 1, 2, 3, 4, 5 };

        foreach (int number in numbers)
        {
            Console.WriteLine($"Number: {number}");
        }
    }
}

Object-Oriented Programming

C# is an object-oriented language, supporting classes, inheritance, polymorphism, and encapsulation.

// Example: Class and Object
using System;

class Person
{
    public string Name { get; set; }
    public int Age { get; set; }

    public void Display()
    {
        Console.WriteLine($"Name: {Name}, Age: {Age}");
    }
}

class Program
{
    static void Main()
    {
        Person person = new Person { Name = "Alice", Age = 25 };
        person.Display();
    }
}

Exception Handling

C# uses try, catch, and finally blocks to handle exceptions gracefully.

// Example: Exception handling
using System;

class Program
{
    static void Main()
    {
        try
        {
            int result = 10 / 0;
        }
        catch (DivideByZeroException ex)
        {
            Console.WriteLine($"Error: {ex.Message}");
        }
        finally
        {
            Console.WriteLine("Execution complete.");
        }
    }
}

LINQ

Language Integrated Query (LINQ) allows you to query collections and databases in a readable and expressive way.

// Example: LINQ
using System;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        List<int> numbers = new List<int> { 1, 2, 3, 4, 5 };
        var evenNumbers = numbers.Where(n => n % 2 == 0);

        foreach (int number in evenNumbers)
        {
            Console.WriteLine($"Even Number: {number}");
        }
    }
}

Asynchronous Programming

C# supports asynchronous programming using async and await keywords, making it easy to write non-blocking code.

// Example: Asynchronous programming
using System;
using System.Threading.Tasks;

class Program
{
    static async Task Main()
    {
        Console.WriteLine("Starting task...");
        await Task.Delay(2000); // Simulate a 2-second delay
        Console.WriteLine("Task completed.");
    }
}