C# Language Documentation

Welcome to the comprehensive documentation for the C# programming language. C# is a modern, object-oriented, and type-safe programming language developed by Microsoft. It is widely used for building a variety of applications, from desktop and web applications to mobile apps and games.

Getting Started

To begin your journey with C#, you'll need to set up your development environment. The most common way is to use Visual Studio or Visual Studio Code with the C# extension.

Prerequisites:

Your First C# Program

Create a new console application project and write the following code:


using System;

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

This simple program outputs "Hello, World!" to the console.

Language Basics

Variables and Data Types

C# is a strongly-typed language. Variables must be declared with a specific data type.


int number = 10;             // Integer
double pi = 3.14159;         // Floating-point number
string message = "Hello";    // String
bool isTrue = true;          // Boolean

Operators

C# supports a wide range of operators for arithmetic, comparison, logical operations, and more.

Arithmetic Operators: +, -, *, /, %

Comparison Operators: ==, !=, <, >, <=, >=

Logical Operators: && (AND), || (OR), ! (NOT)

Control Flow

Control flow statements allow you to direct the execution of your program.


if (number > 5)
{
    Console.WriteLine("Number is greater than 5.");
}
else if (number == 5)
{
    Console.WriteLine("Number is 5.");
}
else
{
    Console.WriteLine("Number is less than 5.");
}

for (int i = 0; i < 5; i++)
{
    Console.WriteLine($"Iteration: {i}");
}

while (isTrue)
{
    Console.WriteLine("This loop will continue indefinitely.");
    isTrue = false; // Prevent infinite loop in example
}

Methods

Methods are blocks of code that perform a specific task.


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

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

Classes and Objects

Classes are blueprints for creating objects. Objects are instances of classes.


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

    public Person(string name, int age)
    {
        Name = name;
        Age = age;
    }

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

// Creating an object
Person person1 = new Person("Alice", 30);
person1.DisplayInfo();

Advanced Topics

Asynchronous Programming

The async and await keywords simplify asynchronous programming, allowing your applications to remain responsive.


public async Task LoadDataAsync()
{
    Console.WriteLine("Starting data load...");
    await Task.Delay(2000); // Simulate network latency
    Console.WriteLine("Data loaded.");
}

LINQ (Language Integrated Query)

LINQ provides a powerful and flexible way to query data from various sources.


List<int> numbers = new List<int> { 5, 1, 4, 2, 8, 3, 7, 6 };
var evenNumbers = numbers.Where(n => n % 2 == 0).OrderBy(n => n);

Console.WriteLine("Even numbers: ");
foreach (var num in evenNumbers)
{
    Console.Write($"{num} ");
}
Console.WriteLine();

Language Features

C# continuously evolves with new features to enhance developer productivity and code expressiveness.

Records

Records are a new class type for primarily data-holding scenarios, offering immutability and value-based equality.


public record Customer(string Name, int Id);

Customer cust1 = new Customer("Bob", 101);
Customer cust2 = new Customer("Bob", 101);
Console.WriteLine(cust1 == cust2); // Output: True

Pattern Matching

Pattern matching allows you to check types and extract data from objects in a concise way.


object data = "Some Text";

if (data is string str)
{
    Console.WriteLine($"It's a string: {str.ToUpper()}");
}

Best Practices

Adhering to best practices ensures code maintainability, readability, and robustness.