IBM Mainframe Forum

Posted: **Wed Sep 12, 2012 7:32 pm**

Hello all
I am struggling with calling C from COBOL. Basically, I need a working sample COBOL calling C with *parm parameters. I was trying to call using BY REFERENCE, I tried to call USING BY REFERENCE to a pointer and it is clear that it does not work. Let me please show you my latest attempt (bear in mind that it is only a test attempt, not the real program):
Here is the COBOL

Select all

000001 identification division.
000002 Program-ID. cobapi.
000003 ENVIRONMENT DIVISION.
000004 data division.
000005 working-storage section.
000006 * int TESTAPI(const char *subject,
000007 * int *ovector, int stringcount,
000008 * const char ***listptr)
000009
000010 01 subject.
000011 05 FILLER PIC X(5) VALUE 'ABCDE'.
000012 05 FILLER PIC X VALUE X'00'.
000013 01 OVECTOR PIC S9(8) VALUE 96.
000014 01 STRINGCOUNT PIC S9(8) VALUE 396.
000015 01 LISTPTR USAGE POINTER VALUE NULL.

000016 01 RESULT PIC S9(8) VALUE 0.
000017 LINKAGE SECTION.
000018 PROCEDURE DIVISION.
000019 CALL 'TESTAPI' USING by content
000020 subject ,
000021 OVECTOR ,
000022 STRINGCOUNT ,
000023 LISTPTR
000024 RETURNING RESULT.
000025 DISPLAY "RESULT " RESULT.
000026 GOBACK.

and here is the C:

Select all

#include "zatoolib.h"
int TESTAPI(const char *subject, int *ovector, int stringcount,
const char ***listptr)
{
printf ("SUBJECT %s\n", *subject);
printf ("OVECTOR %d\n", *ovector);
/*intf ("STRINGCOUNT %d\n", stringcount);*/
/*printf ("LISTPTR %s\n", ***listptr); */
return 100;
}

and the results on the mainframe:

Select all

SUBJECT
OVECTOR 293264496

RESULT 0000000{

Obviously, not what I expected.
The COBOL compiler is IBM Enterprise COBOL for z/OS 3.3.1
The C is 15647A01 V2 R10 OS/390 C

Any suggestions what am I doing wrong

I do not use the #pragma linkage... this would be my next attempt tonight.
Thanks
ZA

Posted: **Wed Sep 12, 2012 7:48 pm**

I googled with this - ibm calling c from Cobol - and got some likely-looking stuff.

Posted: **Wed Sep 12, 2012 8:41 pm**

It did not work for me and I don't know why.
ZA

Posted: **Wed Sep 12, 2012 8:57 pm**

Hello,

What happens if you call your c module from another c module? Run it standalone?

Posted: **Wed Sep 12, 2012 9:03 pm**

I don't know why.

no wonder...

You simply did not read about the correspondence between C and COBOL datatypes
for example here :
http://publib.boulder.ibm.com/infocente ... clcccd.htm
and here :
http://publib.boulder.ibm.com/infocente ... clccce.htm

Posted: **Thu Sep 13, 2012 2:35 am**

follow on ...
I strongly recommend You to meditate on

http://publibz.boulder.ibm.com/cgi-bin/ ... 0602121454

chapter 4 for COBOL
chapter 8 for PL/I

Posted: **Thu Sep 13, 2012 5:09 am**

Any suggestions what am I doing wrong

1. int in C is NOT PIC S9(8) in COBOL -- you're missing something
2. The manual, as enrico indicates, will give you a lot of help
3. It's not clear whether some of the errors in your code are deliberate mistakes or not.

Posted: **Thu Sep 13, 2012 7:57 am**

The mistake of not declaring the integers as S9(8) BINARY, which was a typo, threw me off. The examples do not cover how to pass a character string without the #pragma, but I will find the answer.
Thanks to all who answered...
This code is meant to teach me how to pass parameters between COBOL and C for the COBOL API that I am writing for the PCRE port to z/OS (which is up and running in pure C environment). Version V0.0b was already published for limited audience, mainly to test the installation procedures.
Any body who is interested can PM me and I will distribute it to you.
I hope to finish the COBOL API soon and come with V0.3b
ZA

Posted: **Thu Sep 13, 2012 8:15 am**

OK,

Select all

#include "zatoolib.h"
int TESTAPI(const char *subject, int *ovector, int stringcount,
const char ***listptr)
{
printf ("SUBJECT %s\n", subject);
printf ("OVECTOR %d\n", *ovector);
printf ("STRINGCOUNT %d\n", stringcount);
/*printf ("LISTPTR %s\n", ***listptr); */
return 100;
}

and

Select all

identification division.
Program-ID. cobapi.
ENVIRONMENT DIVISION.
data division.
working-storage section.
* int TESTAPI(const char *subject,
* int *ovector, int stringcount,
* const char ***listptr)

01 subject.
05 FILLER PIC X(5) VALUE 'ABCDE'.
05 FILLER PIC X VALUE X'00'.
01 OVECTOR PIC S9(8) COMP VALUE 96.
01 STRINGCOUNT PIC S9(8) COMP VALUE 396.
01 LISTPTR USAGE POINTER VALUE NULL.

01 RESULT PIC S9(8) COMP VALUE 0.
01 LIST1 USAGE POINTER VALUE NULL.

01 LIST2 USAGE POINTER VALUE NULL.

LINKAGE SECTION.
PROCEDURE DIVISION.
set list1 to ADDRESS OF subject
set list1 to ADDRESS OF OVECTOR
CALL 'TESTAPI' USING
by content subject ,
by reference OVECTOR ,
* list1
* list2
by value STRINGCOUNT ,
LISTPTR
RETURNING RESULT.
DISPLAY "RESULT " RESULT.
GOBACK.

work fine. The only issue is how to address something like the

Select all

const char ***listptr

Thanks
ZA

IBM Mainframe Forum

sample COBOL calling C with *parm parameters

sample COBOL calling C with *parm parameters

Re: sample COBOL calling C with *parm parameters

Re: sample COBOL calling C with *parm parameters

Re: sample COBOL calling C with *parm parameters

Re: sample COBOL calling C with *parm parameters

Re: sample COBOL calling C with *parm parameters

Re: sample COBOL calling C with *parm parameters

Re: sample COBOL calling C with *parm parameters

Re: sample COBOL calling C with *parm parameters