C# Overview - .NET Docs

C# Language Overview

C# is a modern, object-oriented, and type-safe programming language developed by Microsoft. It runs on the .NET platform and is designed for building a wide range of applications, from desktop and web applications to mobile apps and cloud services. C# combines the power of C++ with the ease of use of Visual Basic.

Key Features of C#

Object-Oriented: C# supports encapsulation, inheritance, and polymorphism, allowing for modular and reusable code.
Type-Safe: The compiler enforces type checking at compile time, reducing runtime errors.
Component-Oriented: C# encourages the development of reusable software components.
Modern Language Constructs: Features like LINQ, async/await, and pattern matching simplify complex programming tasks.
Garbage Collection: Automatic memory management frees developers from manual memory allocation and deallocation.
Interoperability: C# integrates seamlessly with other languages and COM components.

Basic Syntax and Structure

A typical C# program consists of classes, which contain methods. Methods define the executable code. Here's a very simple "Hello, World!" example:


using System;

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

In this example:

using System; imports the System namespace, which contains essential classes like Console.
public class HelloWorld declares a class named HelloWorld.
public static void Main(string[] args) is the entry point of the application. The Main method is executed when the program starts.
Console.WriteLine("Hello, World!"); prints the string "Hello, World!" to the console.

Fundamental Data Types

C# provides a rich set of built-in data types:

Integral Types: sbyte, byte, short, ushort, int, uint, long, ulong
Floating-Point Types: float, double, decimal
Boolean Type: bool (true or false)
Character Type: char (a single Unicode character)
String Type: string (a sequence of Unicode characters)

Example declaration:


int age = 30;
string name = "Alice";
double price = 19.99;
bool isActive = true;

Variables and Constants

Variables are used to store data. Constants, declared using the const keyword, store values that cannot be changed after they are initialized.


// Variable
int counter = 10;
counter = 20; // Valid

// Constant
const double PI = 3.14159;
// PI = 3.0; // This would cause a compile-time error

Control Flow Statements

C# offers various control flow statements to manage the execution path of your program:

Conditional Statements: if, else if, else, switch
Looping Statements: for, foreach, while, do-while
Branching Statements: break, continue, return, goto

Object-Oriented Programming (OOP) Concepts

C# fully embraces OOP principles:

Classes and Objects: Classes are blueprints, and objects are instances of those blueprints.
Encapsulation: Bundling data (fields) and methods that operate on the data within a single unit (class).
Inheritance: Allowing a new class to inherit properties and behaviors from an existing class.
Polymorphism: The ability of an object to take on many forms, often through method overriding and overloading.

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