C# Tutorial

C# (pronounced C-Sharp) is a modern, object-oriented programming language developed by Microsoft. It is widely used for building web applications, desktop applications, cloud services, games, and enterprise software.

• C# runs on .NET, enabling applications to run across Windows, macOS, and Linux.
• Its syntax is similar to other C-based languages such as Java and C++.

Hello World Program

using System;

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

Hello, World!

Why Learn C#?

• Object-oriented and strongly typed programming language.
• Used for web, desktop, cloud, and enterprise application development.
• Widely used with ASP.NET Core for backend and web development.
• Popular for game development with Unity.
• Supported by the modern cross-platform .NET ecosystem.

Basics

Before learning C# programming concepts, install and set up the .NET SDK, install and set up Visual Studio Code for C#, and set up the required environment variables to create and run C# programs.

• Introduction
• Input and Output
• Identifiers
• Keywords
• Variables
• Data Types
• Constants and Literals
• Type Casting
• Comments
• Operators
• Decision Making
• Loops and Jump Statements

Methods

C# methods are reusable blocks of code that perform specific tasks. They help organize programs, reduce code duplication, and improve readability.

• Methods in C#
• Method Parameters
• Return Types
• Method Overloading
• Optional and Function Parameters
• ref, out, and in Parameters
• Recursion

Arrays

C# arrays store multiple values of the same type in a single variable. Elements are accessed using indexes, making arrays useful for organizing fixed-size collections of data.

• Introduction to Arrays
• Multidimensional Arrays
• Jagged Arrays
• Array Class
• Sorting an Array

Strings

C# strings represent sequences of characters and are widely used for text processing. The language provides several built-in features for creating, formatting, comparing, and manipulating strings.

• Introduction to String
• String Formatting
• String Interpolation
• Verbatim String
• StringBuilder
• String Class
• String vs StringBuilder

Object-Oriented Programming (OOP)

C# follows the Object-Oriented Programming paradigm, which organizes programs using classes and objects. OOP concepts help developers create modular, reusable, and maintainable applications.

• Classes and Objects
• Methods
• Constructors
• Destructors
• Properties
• Access Modifiers
• this Keyword
• Static Members
• Encapsulation
• Inheritance
• Polymorphism
• Abstraction
• Interfaces and Abstract Classes

Collections

C# collections are used to store and manage groups of objects dynamically. Generic collections provide type safety and are generally preferred for modern C# development.

• List
• LinkedList
• HashSet
• SortedSet
• Dictionary
• SortedDictionary
• Stack
• Queue
• ArrayList
• Hashtable
• SortedList
• BitArray

Generics

Generics allow developers to create reusable classes and methods that work with different data types while maintaining compile-time type safety.

• Introduction to Generics
• Generic Classes
• Generic Methods
• Generic Interfaces
• Generic Constraints
• Generic Collections

Exception Handling

C# Exception Handling provides a structured mechanism for handling runtime errors. It allows programs to respond to exceptional situations without terminating unexpectedly.

• Exception Handling
• Try-Catch Block
• Finally Block
• Throw Keyword
• Multiple Catch Clauses
• Custom Exceptions
• Exception propagation

Delegates and Events

Delegates are type-safe references to methods and form an important foundation for callbacks, events, and functional-style programming in C#.

• Delegates
• Anonymous Methods
• Events
• Event Handlers
• Action Delegate
• Func Delegate
• Predicate Delegate

Lambda Expressions

Lambda expressions provide a concise way to define anonymous functions. They are commonly used with delegates, collections, asynchronous APIs, and LINQ.

• Lambda Expressions
• Lambda with Delegates
• Lambda with LINQ

LINQ

LINQ (Language Integrated Query) allows developers to query and transform data directly within C#. It can work with collections, objects, databases, XML, and other data sources.

• Introduction to LINQ
• Query Syntax
• Method Syntax
• LINQ Operators and Methods
• Filtering
• Sorting
• Projection
• Grouping
• Aggregation

File Handling

C# File Handling enables applications to create, read, write, and manage files and directories. File operations are primarily provided through classes in the System.IO namespace.

• File Handling
• File Class
• FileInfo Class
• Directory and DirectoryInfo
• FileStream
• StreamReader and StreamWriter
• BinaryReader
• BinaryWriter

Multithreading and Asynchronous Programming

C# supports concurrent and asynchronous programming using threads, tasks, and async/await. Modern C# applications commonly use higher-level abstractions such as Task and asynchronous APIs.

• Introduction to Multithreading
• Types of Threads
• Creating Threads
• Main Thread
• Thread Lifecycle
• Thread Class
• Thread Synchronization
• Thread Safety and Race Conditions
• Locks
• Task Parallel Library (TPL)
• Tasks
• Async and Await

.NET and CLR

.NET is the development platform on which modern C# applications run. Understanding its runtime and execution model helps developers understand how C# code is compiled, executed, and managed.

• Introduction to .NET
• .NET Framework
• .NET vs .NET Framework
• Common Language Runtime (CLR)
• Intermediate Language (IL)
• JIT Compilation
• Common Type System (CTS)
• Common Language Specification (CLS)
• Managed and Unmanaged Code
• Garbage Collection
• Assemblies

Advanced C#

Advanced C# covers language features used to create flexible, expressive, and maintainable applications.

• Extension Methods
• Pattern Matching
• Attributes
• Nullable Types
• Nullable Reference Types
• Tuples
• Records
• Indexers
• Iterators
• Reflection

Database Connectivity

C# applications can communicate with relational databases using .NET data-access technologies. ADO.NET provides classes for establishing connections, executing commands, and processing database results.

• Introduction to ADO.NET
• Database Connection
• Connection Class
• Command
• DataReader
• DataAdapter
• DataSet
• Parameterized Queries
• Transactions
• CRUD Operations

Quiz and Coding Practice

Practice C# concepts through topic-wise quizzes and coding problems to improve programming knowledge and problem-solving skills.

• C# Topic-wise Quiz
• C# Coding Practice Problems

Interview Questions

This section helps learners revise important C#, .NET, OOP, collections, LINQ, multithreading, and application-development concepts for technical interviews.

• C# Interview Questions and Answers
• .NET Interview Questions
• ASP.NET Interview Questions