MSDN Documentation

Introduction to C#

C# (pronounced "C sharp") is a modern, object-oriented, and type-safe programming language developed by Microsoft. It is designed to enable developers to build a wide range of applications for the Microsoft .NET platform, from web services and desktop applications to mobile apps and games.

C# combines the high productivity of a component-oriented language with the raw power and flexibility of C-like languages. It has a rich type system and an extensive library that supports common programming tasks.

Getting Started

To begin programming in C#, you'll need to install the .NET SDK. This includes the C# compiler and the necessary runtime environment.

1. Download and Install .NET SDK: Visit the official .NET download page.
2. Choose an IDE: Visual Studio (Community, Professional, Enterprise) or Visual Studio Code with the C# Dev Kit extension are popular choices.
3. Create Your First Project: Open your IDE, create a new Console Application project, and write your first "Hello, World!" program.

// Hello, World! Program
using System;

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

Basic Concepts

Understanding the fundamental building blocks of C# is crucial for effective programming.

Variables and Data Types

Variables are named storage locations that hold data. C# is statically typed, meaning the type of a variable must be declared explicitly.

Type	Description	Example
int	32-bit signed integer.	int age = 30;
string	Sequence of characters.	string name = "Alice";
double	64-bit floating-point number.	double price = 99.99;
bool	True or false value.	bool isComplete = false;

Operators

Operators are symbols that perform operations on variables and values.

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

Control Flow Statements

Control flow statements determine the order in which code is executed.

• Conditional: if, else if, else, switch
• Loops: for, while, do-while, foreach
• Branching: break, continue, return

if (score > 90)
{
    Console.WriteLine("Excellent!");
}
else if (score > 70)
{
    Console.WriteLine("Good.");
}
else
{
    Console.WriteLine("Needs Improvement.");
}

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

Object-Oriented Programming (OOP)

C# is a powerful object-oriented language. OOP paradigms help in organizing code into reusable and maintainable modules.

Classes and Objects

A class is a blueprint for creating objects. An object is an instance of a class.

public class Car
{
    public string Model;
    public int Year;

    public void StartEngine()
    {
        Console.WriteLine($"The {Model}'s engine is starting.");
    }
}

// Creating an object (instance) of the Car class
Car myCar = new Car();
myCar.Model = "Sedan";
myCar.Year = 2023;
myCar.StartEngine(); // Output: The Sedan's engine is starting.

Inheritance

Inheritance allows a new class (derived class) to inherit properties and methods from an existing class (base class).

public class Vehicle {}
public class Truck : Vehicle { /* Truck inherits from Vehicle */ }

Polymorphism

Polymorphism means "many forms." It allows objects of different classes to be treated as objects of a common base class.

Achieved through method overriding and interfaces.

Encapsulation

Encapsulation is the bundling of data (fields) and methods that operate on the data within a single unit (class). It also involves controlling access to the data using access modifiers (public, private, protected).

Advanced Topics

Generics

Generics provide a way to define type-safe classes, interfaces, and methods that can operate on different types without compromising type safety.

// Generic list
List<int> numbers = new List<int>();
numbers.Add(10);

List<string> names = new List<string>();
names.Add("Bob");

Delegates and Events

Delegates are type-safe function pointers. Events are a mechanism that allows a class to notify other classes when something happens.

Asynchronous Programming

The async and await keywords simplify writing asynchronous code, allowing applications to remain responsive while performing long-running operations.

public async Task<string> DownloadDataAsync(string url)
{
    using (HttpClient client = new HttpClient())
    {
        string result = await client.GetStringAsync(url);
        return result;
    }
}

Newer Language Features

C# continuously evolves with new features introduced in various versions:

• LINQ (Language Integrated Query)
• Lambda Expressions
• Extension Methods
• Pattern Matching
• Record Types
• Nullable Reference Types
• Top-level Statements
• Record Structs

Best Practices

Follow these guidelines for robust and maintainable C# code:

• Use meaningful names for variables, methods, and classes.
• Adhere to naming conventions (e.g., PascalCase for classes and methods, camelCase for local variables).
• Write clear, concise code with appropriate comments where necessary.
• Utilize modern C# features to improve readability and efficiency.
• Handle exceptions gracefully.
• Strive for immutability where appropriate.
• Write unit tests to ensure code correctness.