C# 0 The Complete Reference

house

 and 

office

 were initialized by the 

Building( )

 constructor when they were 

created. Each object is initialized as specified in the parameters to its constructor. For 

example, in the following line,

Building house = new Building(2, 2500, 4);

the values 2, 2500, and 4 are passed to the 

Building( )

 constructor when 

new

 creates the 

object. Thus, 

house

’s copy of 

Floors

,

Area

, and 

Occupants

 will contain the values 2, 2500, 

and 4, respectively.

The new Operator Revisited

Now that you know more about classes and their constructors, let’s take a closer look at the 

new

 operator. As it relates to classes, the 

new

 operator has this general form:

new

class-name

(

arg-list

)

Here, 

class-name

 is the name of the class that is being instantiated. The class name followed 

by parentheses specifies the constructor for the class. If a class does not define its own 

constructor, 

new

 will use the default constructor supplied by C#. Thus, 

new

 can be used 

to create an object of any class type.

Since memory is finite, it is possible that 

new

 will not be able to allocate memory for an 

object because insufficient memory exists. If this happens, a runtime exception will occur. 

(You will learn how to handle exceptions in Chapter 13.) For the sample programs in this 

book, you won’t need to worry about running out of memory, but you may need to consider 

this possibility in real-world programs that you write.

Using new with Value Types

At this point, you might be asking why you don’t need to use 

new

 for variables of the value 

types, such as 

int

 or 

float

? In C#, a variable of a value type contains its own value. Memory 

to hold this value is automatically provided when the program is run. Thus, there is no 

need to explicitly allocate this memory using 

new

. Conversely, a reference variable stores 

a reference to an object. The memory to hold this object must be allocated dynamically, 

during execution.

Not making the fundamental types, such 

int

 or 

char

, into reference types greatly 

improves your program’s performance. When using a reference type, there is a layer of 

indirection that adds overhead to each object access. This layer of indirection is avoided by 

a value type.

As a point of interest, it is permitted to use 

new

 with the value types, as shown here:

int i = new int();

Doing so invokes the default constructor for type 

int

, which initializes 

i

 to zero. For example:

// Use new with a value type.

using System;

class newValue {

  static void Main() {

    int i = new int(); // initialize i to zero

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