C# 3.0 Pocket Reference, 2nd Edition

A First C# Program

Here is a program that multiplies 12 x 30, and prints the result, 360, to the screen. The double-forward slash indicates that the remainder of a line is a comment.

	using System;                 // importing namespace

	class Test                    // class declaration
	{
	  static void Main( )         //   method declaration
	  {
	    int x = 12 * 30;          //     statement 1
	    Console.WriteLine (x);    //     statement 2
	  }                           //   end of method
	}                             // end of class

At the heart of this program lie two statements. Statements in C# execute sequentially. Each statement is terminated by a semicolon:

	int x = 12 * 30; 
	Console.WriteLine (x);

The first statement computes the expression 12 * 30 and stores the result in a local variable, named x, which is an integer type. The second statement calls the Console class’s WriteLine method to print the variable x to a text window on the screen.

A method performs an action in a series of statements, called a statement block—a pair of braces containing zero or more statements. We defined a single method named Main:

	static void Main( )
	{
	  ...
	}

Writing higher-level functions that call upon lower-level functions simplifies a program. We can refactor our program with a reusable method that multiplies an integer by 12 as follows:

	using System;

	class Test
	{
	  static void Main( )
	  {
	    Console.WriteLine (FeetToInches (30));    // 360
	    Console.WriteLine (FeetToInches (100));   // 1200
	  }

	  static int FeetToInches (int feet)
	  {
	    int inches = feet * 12;
	    return inches;
	  }
	}

A method can receive input data from the caller by specifying parameters ...