. Net basic learning (iterator)

The most common method to create an iterator isIenumerableInterface implementationGetenumeratorMethod

For example, the implementation of the output A-Z:

 
Public Class A {public system. collections. ienumerator getenumerator () {for (INT I = 65; I <= 90; I ++) {yield return (char) I ;}}}
 

The call method is as follows:GetenumeratorThe method makes the type an enumerated type and allows the use of foreach statements.

 
Static void main (string [] ARGs) {foreach (char I in new A () {console. Write (I );}}
 

Foreach statement callInstance. getenumerator ()The returned enumerated values are used for loop access.

Running result diagram:

You can also use the named iterator to support cyclically accessing the same data set in different ways. For example, you can provide an iterator for returning elements in ascending order, and another iterator for returning elements in descending order. The iterator can also contain parameters to allow the client to control all or part of the iteration behavior. The following iterator uses the named iteratorSampleiteratorImplementationIenumerableInterface:

Public Class B {public system. collections. ienumerable sampleiterator (INT start, int end) {for (INT I = start; I <= end; I ++) {yield return I ;}}}
 

The calling method of the named iterator is as follows:

 
Static void main (string [] ARGs) {foreach (int I in new B (). sampleiterator (1, 10) {console. Write (I );}}
 

The running result is shown as follows:

Multiple yield statements can be used in the same iterator, as shown in the following example:

 
Public class c {public system. Collections. ienumerator getenumerator () {yield return "Bo"; yield return ""; yield return ""; yield return ". ";}}
 

Then you can use the following foreach statement to output the result:

 
Static void main (string [] ARGs) {foreach (string s in new C () {console. Write (s );}}
 

Running result:

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