RE: CWCCVTDT continued....

Scott,
You're right of course, and I actually just posted a similar comment about 30
minutes ago. Thanks.

-Bob Cozzi
www.RPGxTools.com
RPG xTools - Enjoy programming again.


-----Original Message-----
From: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx] On
Behalf Of Scott Klement
Sent: Tuesday, February 28, 2006 3:25 PM
To: RPG programming on the AS400 / iSeries
Subject: RE: CWCCVTDT continued....


>     D QWCCVTDT        PR                  ExtPgm('QWCCVTDT')
>     D  inFmt                        10A   Const OPTIONS(*VARSIZE)
>     D  inDate                       64A   Const OPTIONS(*VARSIZE)
>     D  outFmt                       10A   Const OPTIONS(*VARSIZE)
>     D  outDate                      64A   OPTIONS(*VARSIZE)
>     D  api_error                          LikeDS(QUSEC)
>     D                                     OPTIONS(*VARSIZE)

The problem with this prototype is all of the OPTIONS(*VARSIZE) all over 
the place.  Can I suggest that you remove them from all but the outDate 
and api_error parameters?

The way you have this coded, you can't use literals unless they're the 
exact length of the parameter.

For example, for the "input format", the API is expecting to receive a 
CHAR(10) field.  Always.  If you use the above prototype and code

       callp QWCCVTDT( '*MDY' . . . )

The prototype will only pass 4 bytes to the API, in spite of the fact that 
the API expects 10.  So now you're forcing the caller to always put his 
formats in variables to make sure that all 10 chars are passed, and that 
makes the API more awkward to use.

Worse, depending on what happens to be in memory, there's a good chance 
that you could call the API (the way it's coded above) and have it work 
MOST of the time, since the memory after the literal might happen to be 
blank or x'00'.  That means that it'd just fail occasionally, likely in 
production, and the bug may never be found.

Prototypes are supposed to protect you from these things, but they won't 
if you're disabling that protection by using OPTIONS(*VARSIZE) everywhere.

So my suggestion is to code the prototype like this:

      D QWCCVTDT        PR                  ExtPgm('QWCCVTDT')
      D  inFmt                        10A   Const
      D  inDate                       20A   Const
      D  outFmt                       10A   Const
      D  outDate                      20A   OPTIONS(*VARSIZE)
      D  api_error                          LikeDS(QUSEC)
      D                                     OPTIONS(*VARSIZE)