C# 0 The Complete Reference

AreaPerPerson( )

 can be used 

in the 

WriteLine( )

 statement directly, as shown here:

Console.WriteLine("house has:\n  " +

                  house.Floors + " floors\n  " +

                  house.Occupants + " occupants\n  " +

                  house.Area + " total area\n  " +

                  house.AreaPerPerson() + " area per person");

In this case, when 

WriteLine( )

 is executed, 

house.AreaPerPerson( )

 is called automatically, 

and its value will be passed to 

WriteLine( )

. Furthermore, you can use a call to 

AreaPerPerson( )

whenever the area-per-person of a 

Building

 object is needed. For example, this statement 

compares the per-person areas of two buildings:

if(b1.AreaPerPerson() > b2.AreaPerPerson())

  Console.WriteLine("b1 has more space for each person");

Use Parameters

It is possible to pass one or more values to a method when the method is called. A value 

passed to a method is called an 

argument. 

Inside the method, the variable that receives 

the argument is called a 

formal parameter,

 or just 

parameter,

 for short. Parameters are 

declared inside the parentheses that follow the method’s name. The parameter declaration 

syntax is the same as that used for variables. The scope of a parameter is the body of its 

method. Aside from its special task of receiving an argument, it acts like any other local 

variable.

Here is a simple example that uses a parameter. Inside the 

ChkNum

 class, the method 

IsPrime( )

 returns 

true

 if the value that it is passed is prime. It returns 

false

 otherwise. 

Therefore, 

IsPrime( )

 has a return type of 

bool

.

// A simple example that uses a parameter.

using System;

class ChkNum {

  // Return true if x is prime.

  public bool IsPrime(int x) {

    if(x <= 1) return false;

    for(int i=2; i <= x/i; i++)

      if((x %i) == 0) return false;

    return true;

  }

}

class ParmDemo {

  static void Main() {

    ChkNum ob = new ChkNum();

    for(int i=2; i < 10; i++)

      if(ob.IsPrime(i)) Console.WriteLine(i + " is prime.");

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