C# - SHARP PROGRAM STRUCTURE
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.
C# Hello World Example
A C# program basically consists of the following parts:
• Namespace declaration
• A class
• Class methods
• Class attributes
• A Main method
• Statements & Expressions
• Comments
Let us look at a simple code that would print the words "Hello World":
using System;
namespace HelloWorldApplication
{
class HelloWorld
{
static void Main(string[] args)
{
/* my first program in C# */
Console.WriteLine("Hello World");
Console.ReadKey();
}
}
}
When the above code is compiled and executed, it produces the following result:
Hello World
Let us look at various parts of the above program:
• The first line of the program using System; - the using keyword is used to include the Systemnamespace in the
program. A program generally has multiple using statements.
• The next line has the namespace declaration. A namespace is a collection of classes. TheHelloWorldApplication
namespace contains the class HelloWorld.
• The next line has a class declaration, the class HelloWorld contains the data and method definitions that your
program uses. Classes generally would contain more than one method. Methods define the behavior of the class.
However, the HelloWorld class has only one methodMain.
• The next line defines the Main method, which is the entry point for all C# programs. The Mainmethod states what
the class will do when executed
• The next line /*...*/ will be ignored by the compiler and it has been put to add additionalcomments in the program.
• 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's 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, file name could be different from the class name.