Iterators

An iterator is a section of code that returns an ordered sequence of values. You can create an iterator by defining a member as an iterator, using iterator-id.

Context:

    Classes
    ValueTypes 
    Interfaces
        Type Members

iterator-specification

iterator-header

Example

Here we use an iterator-id paragraph GetEven to return the even numbers in the FibonacciArray

    01 m-FibonacciArray binary-long occurs any static.
    01 anyNumber    binary-long.
    procedure division 
       ...
       set content of m-FibonacciArray to (1 2 3 5 8 13 21 34 55 89 144)

        display "Even numbers"         
        perform varying evenNumbers through iterators::GetEven
            display evenNumbers
        end-perform

    iterator-id GetEven static.
    01 i binary-long.
    procedure division yielding res as binary-long.
        perform varying i through m-FibonacciArray
            if i b-and 1 = 0
                set res to i
                goback
            end-if
        end-perform
        stop iterator *> stops the iterator immediately
    end iterator.     *> stops the iterator implicitly

See also the Iterators sample, which is available from $COBDIR/demo.

Further information

If you specify parameters in the iterator header, you must not include a procedure division header in the body of the iterator.

The STOP ITERATOR statement stops the iteration.

This statement is not needed if the next statement is END ITERATOR.