RE: [Re: RPGILE V4.3 Gotcha]

Joel wrote:
>Have you looked at the manual on precision for intermediate results for
>eval?  The default precision will often produce downright odd results.  You
>can use EXPROPTS(*RESDECPOS) in an H spec to make all  intermediate results
>in expression evaluation have the same precision as the result field, or use
>the "r" operation extender with eval.  The manual gives some interesting
>cautions including that the result of the expression may only be a packed
>field.

"...the result of the expression may only be a packed field."???
Where does it say that in the manual?

I thought the manual said that *RESDECPOS only applies to decimal
operations.  *RESDECPOS is a solution for a problem that occurs
only for decimal numerics, and not for the other numeric data
types.

BTW, in RPG III programming, you probably used packed the most
since it had the best performance of all numeric data types.
But in ILE RPG IV, best numeric performance is achieved using
integer and unsigned data types.  So, use packed decimal only
when you actually have digits to the right of the decimal point.

>
>The default precision rule is designed to guard against overflow.  Of
>course, we always do that in programming and data base design anyway. <g>
>I've fooled around with the precision stuff some, and have had pretty good
>results with the "r".  Personally, I'd rather that "r" were the default, and
>try to guard against overflow myself.

RPG will still tell you when your expressions overflow.  There
just might be a greater possibility of it with *RESDECPOS.

Also, as I've stated before, it's still not a complete solution
since it doesn't apply for expressions that have no associated
result, such as conditional expressions.

Cheers!  Hans

Hans Boldt, ILE RPG Development, IBM Toronto Lab, boldt@ca.ibm.com


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