O'Reilly logo

C# 3.0 Pocket Reference, 2nd Edition by Joseph Albahari, Ben Albahari

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

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 ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required