C# 0 The Complete Reference

ThreeD

’s

operator+( )

 is automatically invoked, and 

b

 will contain the coordinate 11, 12, 13.

One last point: Although you cannot overload the 

[ ]

 array indexing operator using an 

operator

 method, you can create indexers, which are described in the next chapter.

Another Example of Operator Overloading

Throughout this chapter we have been using the 

ThreeD

 class to demonstrate operator 

overloading, and in this regard it has served us well. Before concluding this chapter, 

however, it is useful to work through another example. Although the general principles 

of operator overloading are the same no matter what class is used, the following example 

helps show the power of operator overloading—especially where type extensibility is 

concerned.

This example develops a four-bit integer type and defines several operations for it. As 

you might know, in the early days of computing, the four-bit quantity was common because 

it represented half a byte. It is also large enough to hold one hexadecimal digit. Since four 

bits are half a byte, a four-bit quantity is sometimes referred to as a 

nybble.

 In the days of 

front-panel machines in which programmers entered code one nybble at a time, thinking in 

terms of nybbles was an everyday affair! Although not as common now, a four-bit type still 

makes an interesting addition to the other C# integers. Traditionally, a nybble is an unsigned 

value.

The following example uses the