C# PROGRAM STRUCTURE

Background

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.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Demo
{
    class Program
    {
        static void Main(string[] args)
        {
            /* my first program in C# */
            Console.WriteLine("Hello World");
            Console.ReadKey();
        }
    }
}

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 HelloWorldApplication 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 contain multiple methods. Methods define the behavior of the class. However, the HelloWorld 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 next line /…/ is ignored by the compiler and it is put to add comments 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.

C# Keywords