On Thu, 23 Oct 2008 04:39:38 +0100, CM Poncelet wrote:
>Try:
>
>SAY 'Enter year'
>PULL YEAR
>DO WHILE \DATATYPE(YEAR,'N')
> SAY 'Invalid date 'YEAR':' enter year, using only numeric digits'
> PULL YEAR
> END
>SAY 'Year is 'YEAR /* this line is just to verify ... */
>
I loathe the top-and-bottom input style. The need for it is
a symptom of a deficiency of control structures in the language.
Would you code assembler this way? What could be done with
SPM?
Better:
SAY 'Enter year'
DO InputYear=1
PULL YEAR
IF DATATYPE(YEAR,'N') THEN LEAVE InputYear
SAY 'Invalid date 'YEAR':' enter year, using only numeric digits'
END InputYear
SAY 'Year is 'YEAR /* this line is just to verify ... */
Best to code a function to put the expression in the
loop control:
SAY 'Enter year'
DO InputYear=1 WHILE \GETYEAR()
SAY 'Invalid date 'YEAR':' enter year, using only numeric digits'
END InputYear
SAY 'Year is 'YEAR /* this line is just to verify ... */
...
GETYEAR PROCEDURE
PULL YEAR
RETURN DATATYPE(YEAR,'N')
Better languages allow a compound in the control expression
(not Rexx):
DO InputYear=1 WHILE (PULL YEAR; DATATYPE(YEAR,'N'))
...
-- gil
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