C# 0 The Complete Reference

IComparable

.

The IEquatable Interface

IEquatable

is implemented by those classes that need to define how two objects should 

be compared for equality. It defines only one method, 

Equals( )

, which is shown here:

bool Equals(T 

obj

)

The method returns 

true

 if 

obj

 is equal to the invoking object and 

false

 otherwise.

IEquatable

 is implemented by several classes and structures in the .NET Framework, 

including the numeric structures, 

Char

,

Int32

,

Boolean

, and 

String

.

The IConvertible Interface

The

 IConvertible

 interface is implemented by all of the value-type structures, 

string

, and 

DateTime

. It specifies various type conversions. Normally, classes that you create will not 

need to implement this interface.

The ICloneable Interface

By implementing the 

ICloneable

 interface, you enable a copy of an object to be made. 

ICloneable

 defines only one method, 

Clone( )

, which is shown here:

object Clone( )

This method makes a copy of the invoking object. How you implement 

Clone( )

determines how the copy is made. In general, there are two types of copies: deep and 

shallow. When a deep copy is made, the copy and original are completely independent. 

Thus, if the original object contained a reference to another object 

O,

 then a copy of 

O

 will 

also be made. In a shallow copy, members are copied, but objects referred to by members 

are not. If an object refers to some other object 

O,

 then after a shallow copy, both the copy 

and the original will refer to the same 

O,

 and any changes to 

O

 affect both the copy and the 

original. Usually, you will implement 

Clone( )

 so that it performs a deep copy. Shallow 

copies can be made by using 

MemberwiseClone( )

, which is defined by 

Object

.

Here is an example that illustrates 

ICloneable

. It creates a class called 

Test

 that contains 

a reference to an object of a class called 

X

.

Test

 uses 

Clone( ) 

to create a deep copy.

// Demonstrate ICloneable.

using System;

class X {

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