C# 0 The Complete Reference

ivar

 (an 

int

 variable) is divided by 3, a whole-number division is 

performed, and the outcome is 33—the fractional component is lost. However, when 

dvar

(a

double

 variable) is divided by 3, the fractional component is preserved.

As the program shows, when you want to specify a floating-point value in a program, 

you must include a decimal point. If you don’t, it will be interpreted as an integer. For 

example, in C#, the value 100 is an integer, but the value 100.0 is a floating-point value.

There is one other new thing to notice in the program. To print a blank line, simply call 

WriteLine( )

 without any arguments.

The floating-point data types are often used when working with real-world quantities 

where fractional components are commonly needed. For example, this program computes 

the area of a circle. It uses the value 3.1416 for pi.

// Compute the area of a circle.

using System;

class Circle {

  static void Main() {

    double radius;

    double area;

    radius = 10.0;

    area = radius * radius * 3.1416;

    Console.WriteLine("Area is " + area);

  }

}

The output from the program is shown here:

Area is 314.16

Clearly, the computation of a circle’s area could not be satisfactorily achieved without the 

use of floating-point data.