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.

 1// Example: Your first C# program
 2using System;
 3
 4class Program
 5{
 6    static void Main()
 7    {
 8        Console.WriteLine("Hello, C# Programming!");
 9    }
10}

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.

1# Example: Running a C# program
2dotnet 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.

 1// Example: Declaring variables
 2using System;
 3
 4class Program
 5{
 6    static void Main()
 7    {
 8        int age = 25;
 9        double height = 5.9;
10        string name = "Alice";
11        bool isStudent = true;
12
13        Console.WriteLine($"Name: {name}, Age: {age}, Height: {height}");
14    }
15}

Control Flow

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

 1// Example: Conditional statement
 2using System;
 3
 4class Program
 5{
 6    static void Main()
 7    {
 8        int age = 18;
 9
10        if (age >= 18)
11        {
12            Console.WriteLine("You are an adult.");
13        }
14        else
15        {
16            Console.WriteLine("You are a minor.");
17        }
18    }
19}

Functions

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

 1// Example: Function
 2using System;
 3
 4class Program
 5{
 6    static int Add(int a, int b)
 7    {
 8        return a + b;
 9    }
10
11    static void Main()
12    {
13        int result = Add(5, 10);
14        Console.WriteLine($"Result: {result}"); // 15
15    }
16}

Arrays and Collections

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

 1// Example: List
 2using System;
 3using System.Collections.Generic;
 4
 5class Program
 6{
 7    static void Main()
 8    {
 9        List<int> numbers = new List<int> { 1, 2, 3, 4, 5 };
10
11        foreach (int number in numbers)
12        {
13            Console.WriteLine($"Number: {number}");
14        }
15    }
16}

Object-Oriented Programming

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

 1// Example: Class and Object
 2using System;
 3
 4class Person
 5{
 6    public string Name { get; set; }
 7    public int Age { get; set; }
 8
 9    public void Display()
10    {
11        Console.WriteLine($"Name: {Name}, Age: {Age}");
12    }
13}
14
15class Program
16{
17    static void Main()
18    {
19        Person person = new Person { Name = "Alice", Age = 25 };
20        person.Display();
21    }
22}

Exception Handling

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

 1// Example: Exception handling
 2using System;
 3
 4class Program
 5{
 6    static void Main()
 7    {
 8        try
 9        {
10            int result = 10 / 0;
11        }
12        catch (DivideByZeroException ex)
13        {
14            Console.WriteLine($"Error: {ex.Message}");
15        }
16        finally
17        {
18            Console.WriteLine("Execution complete.");
19        }
20    }
21}

LINQ

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

 1// Example: LINQ
 2using System;
 3using System.Linq;
 4using System.Collections.Generic;
 5
 6class Program
 7{
 8    static void Main()
 9    {
10        List<int> numbers = new List<int> { 1, 2, 3, 4, 5 };
11        var evenNumbers = numbers.Where(n => n % 2 == 0);
12
13        foreach (int number in evenNumbers)
14        {
15            Console.WriteLine($"Even Number: {number}");
16        }
17    }
18}

Asynchronous Programming

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

 1// Example: Asynchronous programming
 2using System;
 3using System.Threading.Tasks;
 4
 5class Program
 6{
 7    static async Task Main()
 8    {
 9        Console.WriteLine("Starting task...");
10        await Task.Delay(2000); // Simulate a 2-second delay
11        Console.WriteLine("Task completed.");
12    }
13}