https://learn.microsoft.com/en-us/dotnet/csharp/

C# (C Sharp)

https://learn.microsoft.com/en-us/dotnet/csharp/

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C# (C Sharp)

C# (pronounced "C sharp") is a modern, object-oriented programming language developed by Microsoft as part of its .NET initiative. Since its introduction in the early 2000s, C# has evolved into a versatile language used for a wide array of applications, including desktop software, web services, mobile apps, and game development. Its design emphasizes simplicity, robustness, and developer productivity, making it a popular choice among programmers.

History and development:

C# was developed in the late 1990s and early 2000s, primarily by Anders Hejlsberg, who is also known for creating Turbo Pascal and leading the design of Delphi. Microsoft announced C# and the .NET Framework in July 2000 as part of its strategy to compete with Sun Microsystems' Java platform.

The language was submitted to the European Computer Manufacturers Association (ECMA) and later to the International Organization for Standardization (ISO) for standardization, ensuring its openness and cross-platform capabilities. Over the years, C# has undergone significant evolution, with major releases introducing new features that keep it modern and competitive.

Key features

Object-oriented programming (OOP)

C# is inherently object oriented, supporting the four main pillars of OOP:

Encapsulation

Bundling data with methods that operate on that data.

Inheritance

Creating new classes from existing classes to promote code reuse.

Polymorphism

Allowing entities to be represented in multiple forms.

Abstraction

Simplifying complex reality by modeling classes appropriate to the problem.

Type Safety

C# is a statically typed language, meaning that type checking occurs at compile time. This reduces runtime errors and enhances code reliability. Features such as nullable types and type inference (var keywords) provide flexibility while maintaining type safety.

Automatic Memory Management

C# uses a garbage collector to manage memory allocation and deallocation automatically. This reduces memory leaks and pointer errors common in languages such as C++ and allows developers to focus on application logic rather than memory management.

Rich Standard Library

The .NET framework provides an extensive class library, offering prebuilt classes for common tasks such as file I/O, networking, and data structures. This accelerates development by reducing the need to write boilerplate code.

Language Integrated Query (LINQ)

Introduced in C# 3.0, LINQ allows developers to write queries directly within C#, providing a consistent model for working with data across various sources, such as collections, XML, and databases.

Asynchronous Programming

C# supports asynchronous programming via the async and await keywords, simplifying the development of applications that perform time-consuming operations without freezing the user interface.

Cross-platform Development

With the introduction of the .NET Core (now known as .NET 5 and above), C# has become truly cross-platform, enabling developers to build applications that run on Windows, macOS, and Linux.

Syntax

Basic structure

A simple C# program:

Variables and Data Types

C# supports various data types, including integers (int), floating-point numbers (float, double), booleans (bool), characters (char), and strings (string). The variables are declared with a type followed by a name:

Control Flow Statements

C# provides standard control flow constructs:Conditional Statements: if, otherwise if, else, switchLoops: for, foreach, while do-whileExample:

Methods

Methods are defined within classes and contain code to perform actions:

Classes and Objects

Classes are blueprints for objects. They contain fields (variables) and methods (functions):

Creating an object:

Inheritance and polymorphism

Inheritance allows a class to inherit members from a base class:

Polymorphism is achieved via virtual and override keywords:

Interfaces

Interfaces define contracts that implementing classes must fulfill:

Delegates and Events

Delegates are type-safe pointers to methods, and events are used with delegates for publish–subscribe patterns:

Generics

Generics allow the creation of classes and methods with a placeholder for the type:

Advanced features

Language Integrated Query (LINQ)

LINQ enables the query of collections via an SQL-like syntax:

Asynchronous Programming

Asynchronous methods improve application responsiveness:

Dynamic Language Features

C# supports dynamic typing via the dynamic keyword, allowing for more flexible code at the cost of compile-time type checking:

Functional Programming Constructs

C# incorporates functional programming elements:

Lambda expressions:

Pattern Matching:

Immutable Data Structures: Using readonly and immutable collections.

Ecosystem and Tools

.NET Framework and.NET Core

Originally, C# was tied to the .NET Framework, which was Windows-only. With the advent of the .NET Core (which is now unified under .NET 5 and later versions), C# applications can run across platforms.