Re: API parm confusion

qsrvbas@xxxxxxxxxxxxx (Tom Liotta) wrote:

>Subject: Re: API parm confusion
>
> Bruce managed to clear up the issue that caused all the confusion in an
> off-line note that I'm going to post my reply to here later.

Just so others will benefit from my blindness after being mostly away from 
COBOL for five years, I'll give the C function prototype for the 
Qp0lGetPathFromFileID() API along with my incorrect COBOL interpretation, and 
then the corrected COBOL.

#include <Qp0lstdi.h>

char *Qp0lGetPathFromFileID(char *buf, size_t size,
                            Qp0lFID_t fileid);

I accessed this API in COBOL with these statements (minus a bunch of irrelevant 
snipped stuff):

       PROCESS
               NOMONOPRC

       Special-names.
                           Linkage type is prc
                               for 'Qp0lGetPathFromFileID'
           .

       01  W-PathPtr                           pointer.
       01  W-BytPrv                        Pic S9(9)
                                               binary.
       01  W-FileID                        Pic X(16).

       01  W-Path                          Pic X(1024).

       90-Get-Path Section.

        90-Initialize.

           set     W-PathPtr       to  NULL
           .

        90-Convert-FileID-to-Path.

           move    1024            to  W-BytPrv

           call 'Qp0lGetPathFromFileID'
               using
                                   W-Path
                   by value        W-BytPrv
                                   W-FileID
               giving
                   W-PathPtr
           end-call

           if  W-PathPtr = null
               move    'N/A'       to  W-Path
           end-if
           .

The corrected portion is:

           call 'Qp0lGetPathFromFileID'
               using
                   by reference    W-Path
                   by value        W-BytPrv
                   by reference    W-FileID
               giving
                   W-PathPtr
           end-call

Explicit coding of BY REFERENCE on the third parm in particular was what I'd 
missed. My personal COBOL coding standards are hereby changed always to include 
explicit BY clauses.

Trivial flaw in coding technique, but what a tough item to see, at least for me.

Tom Liotta

--
Tom Liotta
The PowerTech Group, Inc.
19426 68th Avenue South
Kent, WA 98032
Phone  253-872-7788
Fax    253-872-7904
http://www.powertechgroup.com



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