Re: Parameter passing RPV III <--> RPG IV vs. RPG IV <--> RPG IV

[Joep Beckeringh <joep@xxxxxxxxxxxxxxxxxxx>]

Charles,

I think you were lucky that it worked. In the caller you have field P@ERR 
defined as 1 byte. When you call CADATE you are passing a pointer to this field. 
Now when CADATE puts '123' in the memory that the pointer points at, the '1' 
ends up in field P@ERR, but '23' ends up in whatever variable happens to sit 
next to P@ERR. It is quite possible that in the memory layout that the RPG III 
compiler generated this did no harm, while in the RPG IV layout it did.

Joep Beckeringh


CWilt@xxxxxxxxxxxx wrote:

> Had the following p-list in an RPG III program:
>
> C           PL@DAT    PLIST                   
> C                     PARM           P@DAT1 10
> C                     PARM           P@FMT1  4
> C                     PARM           P@DAT2 10
> C                     PARM           P@FMT2  4
> C                     PARM           P@OPER  1
> C                     PARM           P@UNIT  1
> C                     PARM           P@DURT  3
> C                     PARM           P@ERR   1
> C                     PARM           P@DUR   5
>
>
> The above p-list was used in a call to an RPG IV program.
> C                     CALL 'CADATE'  PL@DAT
>  *                                         
> C           P@ERR     IFEQ '0'             
>
>
> We converted this program to RPG IV using CVTRPGSRC.  During the first use,
> it went into an endless loop.  While debugging, we realized that the P@ERR
> parameter in the called program was 3 chars long and not 1.  All zeros meant
> no error, while anything else ( '001', '002', '003',...'006') would be an
> error.
>
> Now the question: we know that the RPG III program has worked in the past
> when invalid data was passed to CADATE, we don't understand why it would
> have failed as an RPG IV program; particularly when the fix was to change
> P@ERR to 3 chars and the comparison to '000'.  Unless the mismatch in the
> parameters had a different effect with an RPG III <--> RPG IV call than they
> did with a RPG IV <--> RPG IV call.  It almost seems as if the RPG III P@ERR
> ended up with the rightmost char and the RPG IV P@ERR ended up with the
> leftmost (as I would expect).
>
> I put together a small RPG III program to test, and it works as you would
> expect the 1 char P@ERR ends up with the leftmost char.
>
> So what the heck was going on?  Thoughts?
>
> Thanks in advance,
> Charles