C# Overview

C# is a modern, general-purpose, object-oriented programming language developed by Microsoft and approved by European Computer Manufacturers Association (ECMA) and International Standards Organization (ISO).

C# was developed by Anders Hejlsberg and his team during the development of .Net Framework.

C# is designed for Common Language Infrastructure (CLI), which consists of the executable code and runtime environment that allows use of various high-level languages on different computer platforms and architectures.

The following reasons make C# a widely used professional language −

• It is a modern, general-purpose programming language
• It is object oriented.
• It is component oriented.
• It is easy to learn.
• It is a structured language.
• It produces efficient programs.
• It can be compiled on a variety of computer platforms.
• It is a part of .Net Framework.

Strong Programming Features of C#

Although C# constructs closely follow traditional high-level languages, C and C++ and being an object-oriented programming language. It has strong resemblance with Java, it has numerous strong programming features that make it endearing to a number of programmers worldwide.

Following is the list of few important features of C# −

• Boolean Conditions
• Automatic Garbage Collection
• Standard Library
• Assembly Versioning
• Properties and Events
• Delegates and Events Management
• Easy-to-use Generics
• Indexers
• Conditional Compilation
• Simple Multithreading
• LINQ and Lambda Expressions
• Integration with Windows

Before we study basic building blocks of the C# programming language, let us look at a bare minimum C# program structure so that we can take it as a reference in upcoming chapters.
Creating Hello World Program

A C# program consists of the following parts −

• Namespace declaration
• A class
• Class methods
• Class attributes
• A Main method
• Statements and Expressions
• Comments

Let us look at a simple code that prints the words "Hello World" −
using System;

namespace MyFirstApplication 

{ 

     class Program 

    { 

       static void Main(string[] args)

      {

           Console.WriteLine("Hello World");

           Console.ReadKey();

      } 

 }

}

Let us look at the various parts of the given program −

The first line of the program using System; - the using keyword is used to include the System namespace in the program. A program generally has multiple using statements.

The next line has the namespace declaration. A namespace is a collection of classes. The MyFirstApplication namespace contains the class Program.

The next line has a class declaration, the class Program contains the data and method definitions that your program uses. Classes generally contain multiple methods. Methods define the behavior of the class. However, the Program class has only one method Main.


The next line defines the Main method, which is the entry point for all C# programs. The Main method states what the class does when executed.

The Main method specifies its behavior with the statement Console.WriteLine("Hello World");

WriteLine is a method of the Console class defined in the System namespace. This statement causes the message "Hello, World!" to be displayed on the screen.


The last line Console.ReadKey(); is for the VS.NET Users. This makes the program wait for a key press and it prevents the screen from running and closing quickly when the program is launched from Visual Studio .NET.

It is worth to note the following points −

• C# is case sensitive.
• All statements and expression must end with a semicolon (;).
• The program execution starts at the Main method.
• Unlike Java, program file name could be different from the class name.