C# 0 The Complete Reference

PART II

C h a p t e r   2 4 :  

C o l l e c t i o n s ,   E n u m e r a t o r s ,   a n d   I t e r a t o r s    

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Using Iterators

As the preceding example shows, it is not difficult to implement 

IEnumerator

 and 

IEnumerable

. However, it can be made even easier through the use of an 

iterator.

 An iterator 

is a method, operator, or accessor that returns the members of a set of objects, one member at 

a time, from start to finish. For example, assuming some array that has five elements, then an 

iterator for that array will return those five elements, one at a time. By implementing an 

iterator, you make it possible for an object of a class to be used in a 

foreach

 loop.

Let’s begin with an example of a simple iterator. The following program is a modified 

version of the preceding program that uses an iterator rather than explicitly implementing