progress-4gl Iterating DO var = start TO finish [BY step]

Example

This iteration changes a value from a starting point to an end, optionally by a specified value for each step. The default change is 1.

DEFINE VARIABLE i AS INTEGER     NO-UNDO.

DO i = 10 TO 15:
    DISPLAY i WITH FRAME x1 6 DOWN .
    DOWN WITH FRAME x1.
END.

Result:

---------------i

        10
        11
        12
        13
        14
        15

You can iterate over dates as well:

DEFINE VARIABLE dat AS INTEGER        NO-UNDO.

DO dat = TODAY TO TODAY + 3:

END.

And over decimals. But then you most likely want to use BY - otherwise an INTEGER would have done just as fine...

DEFINE VARIABLE de AS DECIMAL     NO-UNDO.

DO de = 1.8 TO 2.6 BY 0.2:
    DISPLAY "Value" de.
END.

Using BY a negative number you can also go from a higher to a lower value:

DEFINE VARIABLE i AS INTEGER     NO-UNDO.

DO i = 5 TO 1 BY -1:
    
END.

The expression will be tested until it's no longer met. This makes the counter be higher (if moving upwards) or lower (if moving downwards) once the loop is finished:

DEFINE VARIABLE i AS INTEGER     NO-UNDO.

DO i = 5 TO 1 BY -1:
    
END.

MESSAGE i. // Will message 0

Another example:

DEFINE VARIABLE da AS DATE     NO-UNDO.

DISPLAY TODAY. //17/02/06
DO da = TODAY TO TODAY + 10:
    
END.
DISPLAY da. //17/02/17 (TODAY + 11)