FYI:

  1. The source code for a C# program is stored in one or more text files with a file extension of .cs, as in test.cs.

  2. Using the command-line compiler provided with Visual Studio or the Net Frame Work, the codes in a program can be compiled with the command line directive

    • csc test.cs
      Successful compilation produces an executable program named test.exe.

  3. "system" directive:  references a namespace called System that is provided by the Microsoft .NET Framework class library.
    • The system namespace contains the Console class referred to in the Main method.
    • The Main method has a static modifier, is the main entry point for a program—the method that is called to begin execution—is always a static method named Main.
 
//It is a Namespace that you need to compile C#
using System;
//everything should be under a class
class test
{
// public variable declaration area

// Main out-put function that will execute to display the result
public static void Main()
{
//out put inside a command window

Console.WriteLine("Welcome to Hello world");
Console.Write("What is your name?: ");
//read input from the commandline
string str = Console.ReadLine();
Console.WriteLine("Hello: " + str);

}
}
 
Let us do some mistake to under the flow.
 
 

No Entry Point: Must have an entry point

//It is a Namepsace that you need to compile C#
//this will not compile
//test_with_noentry.cs
using System;
//everyting should be under a class
class test
{
// public variable declaration area

// Main out-put function that will execute to display the result
//public static void Main()
void Main()
{
//out put inside a command window

Console.WriteLine("Welcome to Hello world");
Console.Write("What is your name?: ");
//read input from the commandline
string str = Console.ReadLine();
Console.WriteLine("Hello: " + str);
}
}

Must have a return data type

//It is a Namepsace that you need to compile C#
//this will not compile
//test_with_novoid.cs
using System;
//everyting should be under a class
class test
{
// public variable declaration area
// Main out-put function that will exucute to display the result
public static Main()
{
//out put inside a command window
Console.WriteLine("Welcome to Hello world");
Console.Write("What is your name?: ");
//read input from the commandline
string str = Console.ReadLine();
Console.WriteLine("Hello: " + str);

}
}