GnuCobol calling C function with arguments - problem when function has more than 2 arguments

Question

I have case like below

testlib.c with two basic functions, one returning value second returning result by reference

int sum(int a, int b) {
    return a + b;
}

void ref(int a, int *b) {
    *b = a * a;
}

compiling library

  gcc -c -static -o testlib.o testlib.c

prg1.cbl calling both C functions "using" by value and by reference


       IDENTIFICATION DIVISION.
       PROGRAM-ID. CallCFunctions.
       
       ENVIRONMENT DIVISION.

       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  A USAGE BINARY-SHORT SIGNED.
       01  B USAGE BINARY-SHORT SIGNED.
       01  C USAGE BINARY-SHORT SIGNED.
       01  R USAGE BINARY-SHORT SIGNED.
       

       PROCEDURE DIVISION.
           MOVE ZERO TO R.
           MOVE ZERO TO C.
           MOVE 4 TO A.
           MOVE 3 TO B.
           MOVE -1 TO C.

           CALL "sum2" USING BY VALUE A B
               RETURNING R
           DISPLAY "Sum2 R = A + B = ", R.

           MOVE ZERO TO R.
           MOVE 13 TO A.
           MOVE ZERO TO B.
           CALL "ref" USING BY VALUE A BY REFERENCE B
           
           DISPLAY "ref B = A * A = ", B.
           

       STOP RUN.

compiling Cobol code

cobc -x -free -o prg1 prg1.cbl testlib.o

Result

Sum2 R = A + B = +00007
ref B = A * A = +00169

which works. Problem starts when I try to call C function with 3 arguments, that is added to my testlib

 int sum3(int a, int b, int c) {
     return a + b + c;
 }

using Cobol code prg2.cbl

       IDENTIFICATION DIVISION.
       PROGRAM-ID. CallCFunctions.
       
       ENVIRONMENT DIVISION.

       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  A USAGE BINARY-SHORT SIGNED.
       01  B USAGE BINARY-SHORT SIGNED.
       01  C USAGE BINARY-SHORT SIGNED.
       01  R USAGE BINARY-SHORT SIGNED.
       

       PROCEDURE DIVISION.
           MOVE ZERO TO R.           
           MOVE 4 TO A.
           MOVE 3 TO B.
           MOVE -1 TO C.
           CALL "sum3" USING BY VALUE A B C
               RETURNING R
           
           DISPLAY R.    

       STOP RUN.

during compilation I get error

   cobc -x -free -o prg2 prg2.cbl testlib.o
   
   prg2.cbl:19: error: syntax error, unexpected C

You should move your solution to an answer (answering your own question) and accept it. That way it is clear that this page contains a solution to the question in the title, not just an unsolved problem. — Fritz, Aug 30 '23 at 12:14
two hints: 1. compile with `-static` - otherwise those two programs are needlessly resolved at run time (or `-k sum2 -k ref`, if you want some CALL literal to be resolved at compile time, while you want others to be "looked up") - or, if you want to stick with GnuCOBOL use `CALL STATIC "sum2"` to make that explicit and don't specify that on command line. 2. to ensure that the second does not try to update the `RETURN-CODE` register: use `CALL "ref2" USING .... RETURNING NOTHING`. — Simon Sobisch, Aug 30 '23 at 12:58

mysiar · Accepted Answer · 2023-09-01T12:47:42.087

For the reason I do not understand problem was with variable names. After changing Cobol code to

       IDENTIFICATION DIVISION.
       PROGRAM-ID. CallCFunctions.
       
       ENVIRONMENT DIVISION.

       DATA DIVISION.
       WORKING-STORAGE SECTION.
       01  VAR-A USAGE BINARY-SHORT SIGNED.
       01  VAR-B USAGE BINARY-SHORT SIGNED.
       01  VAR-C USAGE BINARY-SHORT SIGNED.
       01  VAR-R USAGE BINARY-SHORT SIGNED.
       

       PROCEDURE DIVISION.
           MOVE ZERO TO VAR-R.           
           MOVE 4 TO VAR-A.
           MOVE 3 TO VAR-B.
           MOVE 1 TO VAR-C.
           CALL "sum3" USING BY VALUE VAR-A VAR-B VAR-C
               RETURNING VAR-R
           
           DISPLAY VAR-R.    

       STOP RUN.

It all works

Please use the edit link on your question to add additional information. The Post Answer button should be used only for complete answers to the question. - [From Review](/review/low-quality-posts/34927671) — OznOg, Aug 31 '23 at 17:13

GnuCobol calling C function with arguments - problem when function has more than 2 arguments

1 Answers1