how to pass in multiple values to a pointer using gnucobol to a c script please

[J McNamara]

I had the AI help me with this c code which i tested.

How to use the cobol interface to send in the values for the integers like 5 and 7 integers in the C code PLEASE help.

I think if i could pass the values to int * values, i could use this thing but i don't know the cobol interface for that. Please help with a hint or any tricks.

I can use this to get data values from gixsql and concatenate without first sending to a file and then ummh ... reloading into a textarea.

Then the operation for writing sql to the textarea in cobjapi will be faster and won't be susceptible as much to something going wrong with that process.

It is pretty cool c code ... right?

thanks

#include <stdio.h>

#include <cstring>

#include <string>


extern "C" {
__declspec(dllexport) char * accumulate_buffer(char *buffer, int *value, int *size) {
static int total = 0; // Keeps track of the accumulated sum
int max_size = *size;

// Convert the integer value to a string
char temp[12]; // Enough to hold a string for a 32-bit int
snprintf(temp, sizeof(temp), "%d", *value);

// Check if the buffer can accommodate the new value
int current_length = strlen(buffer);
int value_length = strlen(temp);
if (current_length + value_length + 1 >= max_size) {

return NULL; // Buffer overflow error
}

// Append the value to the buffer
strcat(buffer, temp);

// Return the buffer
return buffer;
}
}

extern "C" {
__declspec(dllexport) void initbuffer(char *buffer, int *values, int *num_values, int *size) {
// Initialize the buffer to an empty string
buffer[0] = '\0';

// Loop through the array of integers
for (int i = 0; i < *num_values; i++) {
if (accumulate_buffer(buffer, &values[i], size) == NULL) {
// Handle buffer overflow
printf("Buffer overflow occurred!\n");
return;
}
}
}
}

the test driver looks like this...

#include <stdio.h>
#include <string.h>

// Declare the function prototypes from the DLL
__declspec(dllimport) char * accumulate_buffer(char *buffer, int *value, int *size);
__declspec(dllimport) void initbuffer(char *buffer, int *values, int *num_values, int *size);

int main() {
    // Define buffer and array for test
    char buffer[100] = "";  // Ensure buffer is initialized to an empty string
    int values[] = {5, 7};  // Example integers
    int num_values = 2;     // Number of values in the array
    int buffer_size = 100;  // Size of the buffer

    // Print the buffer before calling the function
    printf("Buffer before call: '%s'\n", buffer);

    // Call initbuffer to accumulate the values into the buffer
    initbuffer(buffer, values, &num_values, &buffer_size);

    // Print the buffer after calling the function
    printf("Buffer after call: '%s'\n", buffer);

    return 0;
}

[J McNamara]

hI -

i tried this but the email is screwing up my formatting a little.

thanks for any assistance. -jim

$ ./dialog.exe
Starting cobsub.cbl

attempt to reference invalid memory address (signal)

WORKING STORAGE.

01 Arg1 PIC X(100) VALUE SPACES.    *> The buffer 01 Arg2 PIC S9(9) COMP OCCURS 2 TIMES. *> Array of integers

01 Arg3 PIC S9(9) COMP VALUE 2.     *> Number of integers in the array

01 Arg4 PIC S9(9) COMP VALUE 100.   *> Buffer size

01 MY-ARRAY.
          05 MY-ELEMENTS PIC 9(4) OCCURS 2 TIMES INDEXED BY IDX.

Procedure Division.
MOVE 5 TO MY-ELEMENTS(1). *> First integer

MOVE 7 TO MY-ELEMENTS(2). *> Second integer


DISPLAY "Buffer before call: " Arg1.

CALL "initbuffer" USING BY REFERENCE Arg1 *> The buffer

BY REFERENCE MY-ARRAY *> Start of the integer array

BY REFERENCE Arg3 *> Number of integers

BY REFERENCE Arg4 *> Buffer size


DISPLAY "Buffer after call: " Arg1


GOBACK.

[Mickey White]

Hey Jim, just wondering, which AI are you using? I found Claude to be pretty good at cobol.

[J McNamara]

Hi Mickey-

I will try out claude.

I use chatgpt - where it does really well is with cobjapi.

Other than that it gets stuck on problems.

thanks

[J McNamara]

Hi Mickey,

Claude can't solve this problem either.

it is worth a try I like having another AI to fool with though.

thanks

[J McNamara]

when i run the following scenario it prints out the following after the value clause.:

$ ./dialog.exeStarting cobsub.cbl
buffer after call: '0001
                    2 '
buffer after call: '0001
                    2 5 '

so you can see i added a 2 and a 5 and it accumulated them but i got that print out from 
c language. I don't see how to get the printout values from c back to cobol.

I might add that I did something a little wrong. I used IDX3 this time instead of a (1) or (2) when I subscripted. I think that helps me with a compiler error.
Like don't do MY-ELEMENTS(1) OR MY-ELEMENTS(2) NEGATORY

SO i will try Ron's guide again with this new fact I learned that I can subscript a different way without a literal 1 constant etc.

I am just wondering though isnt it supposed to be able to send that value back somehow "the buffer after call : '0001
                         2 5' 
when I am finished in c language?

thanks. It would be a tremendous help. Sorry that I am so spacy. jim :-)

WORKING STORAGE.
01 MY-ARRAY.          05 MY-ELEMENTS PIC S9(4) COMP OCCURS 2 TIMES INDEXED BY IDX3.
       01 WS-BUFFER        PIC X(100) VALUE 'HELLO ME'.
 01 WS-BUFFER-SIZE   PIC 9(4) COMP VALUE 1000.
PROCEDURE DIVISION.

MOVE 1 TO IDX3       MOVE 1 TO MY-ELEMENTS(IDX3) .
       MOVE MY-ELEMENTS(IDX3) TO WS-BUFFER
       CALL "accumulate_buffer"
           USING BY REFERENCE WS-BUFFER
                 BY REFERENCE 2
                 BY REFERENCE WS-BUFFER-SIZE.

       MOVE 2 TO IDX3
       MOVE 2 TO MY-ELEMENTS(IDX3) .
       CALL "accumulate_buffer"
           USING BY REFERENCE WS-BUFFER
                 BY REFERENCE 5
                 BY REFERENCE WS-BUFFER-SIZE

#include <stdio.h>#include <cstring>

extern "C" {
    __declspec(dllexport) char * accumulate_buffer(char *buffer, int *value, int *size) {
        char temp[20]; // Enough to hold a string for a 32-bit integer
       //  char t1[15]="goodebyebye\0";
        snprintf(temp, sizeof(temp), "%d", *value);  // Convert integer to string

        int current_length = strlen(buffer);
        int value_length = strlen(temp);
        if (current_length + value_length + 1 >= *size) {
            return NULL;  // Buffer overflow check
        }

        strcat(buffer, temp);  // Append the integer string to the buffer
        strcat(buffer, " ");  // Add a space separator
        printf("buffer after call: '%s' \n", buffer);

        return buffer;
    }

  __declspec(dllexport) void initbuffer(char *buffer, int *values, int *num_values, int *size) {
// function not used       
 // Initialize the buffer to an empty string
        buffer[0] = '\0';  // Ensures the buffer starts as an empty string

        // Loop through the array of integers
        for (int i = 0; i < *num_values; i++) {
            // Attempt to accumulate the current integer into the buffer
            if (accumulate_buffer(buffer, &values[i], size) == NULL) {
                // Handle buffer overflow
                printf("Buffer overflow occurred!\n");
                return;  // Exit the function if buffer overflow occurs
            }


}

}
int main() {
//none of this code ran
    char buffer[100];  // Buffer to accumulate the values
    int values[] = {5, 7};  // Example values to accumulate
    int num_values = 2;  // Number of integers
    int size = 100;  // Size of the buffer

    // Call initbuffer to accumulate values into the buffer
    initbuffer(buffer, values, &num_values, &size);

    // Display the result
    printf("Buffer after call: '%s'\n", buffer);

    return 0;
}
}

[J McNamara]

Hey all,

I think I got it....
Here is a link which explains more or less what I am trying to do...

https://stackoverflow.com/questions/73160885/getting-a-64-bit-return-value-from-a-c-function-in-gnu-cobol

I will try after midnight it is time to sleep.

Thanks for being patient.

thanks,
jim

[Ralph Linkletter]

MOVE 1 TO IDX3 MOVE 1 TO MY-ELEMENTS(IDX3) .
Should be SET IDX3 TO 1

MOVE 2 TO IDX3
Should be SET IDX3 TO

Letter of the law zOS, MF, and Fujitsu COBOL wise is the use of SET for INDEXED BY variable.
Perhaps GnuCOBOL does not regard this axiom ?

Using MF or Fujitsu this statement MOVE 2 TO IDX3 results in this compiler diagnostic:
Severe Error: 'IDX3' IN MOVE STATEMENT MUST BE IDENTIFIER. 'IDX3' IGNORED.

Your usage did compile okay with GnuCOBOL

[Simon Sobisch]

GnuCOBOL currently does not imply a hard check here and allows also MOVE and computational statements (while it should only allow SET and PERFORM to adjust indexes).

[Mickey White]

I don't see the dialog cbl program. But here is a call I did to a c program and Simon had me to add the SIZE IS parameter . Perhaps you have differing sizes for integers... ?

           call 'mmap' using
               by value     0,
               by value size is 8    mmap-size,
               by value     1,
               by value     1,
               by value size is 8   mmap-hndl-x,
               by value     0,
               returning    mmap-ptr
           end-call

[Mickey White]

I do not know, but C and GnuCOBOL and Json may have all different sizes for binary-long on Linux vs Windows vs MinGW vs Msys
Here is what my Ubuntu 64bit says

BINARY-C-LONG: 8
BINARY-CHAR: 1
BINARY-DOUBLE: 8
BINARY-LONG: 4
BINARY-SHORT: 2

[Simon Sobisch]

COBOL uses BY REFERENCE as standard.

As you want to pass data between COBOL<->C, use the binary types (BINARY-LONG is your common int), as those have the expected size, non-truncation, and byte-order.

To access a table that has only those in a OCCURS.

I'd use the following as a first untested try:

COBOL:

77 VAL1 USAGE BINARY-LONG.
77 VAL2 USAGE BINARY-LONG.
78 ELEMENTS VALUE 50.
01 INTTAB. 05 VAL OCCURS ELEMENTS USAGE BINARY-LONG.
CALL "cprog" USING va1, val2, inttab, BY VALUE elements.

C:

int cprog (int *val1, int *val2, int *tab, int elements) {
   *val1 = *val2;
   for (int i = 0; i < elements; i++) {
      tab[i] = i;
   }
}

Then compile as cobc -xg prog.cob stuff.c and see what the results are - run gdb ./prog to check for strange results.

[Ralph Linkletter]

Separating COBOL from C
COMP-5

       IDENTIFICATION DIVISION.
       PROGRAM-ID. PROG.
       ENVIRONMENT DIVISION.
       INPUT-OUTPUT SECTION.
       FILE-CONTROL.
       DATA DIVISION.
       FILE SECTION.
       WORKING-STORAGE SECTION.
       77  VAL1 PIC 9(08) COMP-5.
       77  VAL2 PIC 9(08) COMP-5.
       77  I    PIC 9(02).
       78  ELEMENTS VALUE 50.
       01  INTTAB.
          05 VAL  OCCURS ELEMENTS TIMES PIC 9(08) COMP-5.
       PROCEDURE DIVISION.
           CALL 'cprog' USING
            VAL1
            VAL2
            INTTAB
            BY VALUE ELEMENTS
            PERFORM VARYING I FROM 1 BY 1 UNTIL I > 50
                DISPLAY 'I=:' I ' VAL=:' VAL (I + 1)
           END-PERFORM
           GOBACK.

Just saying those uninitiated to COBOL should probably see COBOL from you :-)

[J McNamara]

Hi Ralph-

It is very cool to receive your help. I have been busy!

I can't wait to make a table viewer for cobjapi but I have to back off of the pace and spend time learning other thing besides just working on 'just that'.

Thanks for all of your cool help.
Have a very nice weekend,
jim

Sent with Proton Mail secure email.

On Friday, January 3rd, 2025 at 12:33 PM, Ralph Linkletter zosralph@users.sourceforge.net wrote:

Separating COBOL from C
COMP-5

IDENTIFICATION

DIVISION

.

PROGRAM

-

ID

.

PROG

.

ENVIRONMENT

DIVISION

.

INPUT

-

OUTPUT

SECTION

.

FILE

-

CONTROL

.

DATA

DIVISION

.

FILE

SECTION

.

WORKING

-

STORAGE

SECTION

.

77

VAL1

PIC

9

(

08

)

COMP

-

5

.

77

VAL2

PIC

9

(

08

)

COMP

-

5

.

77

I

PIC

9

(

02

).

78

ELEMENTS

VALUE

50

.

01

INTTAB

.

05

VAL

OCCURS

ELEMENTS

TIMES

PIC

9

(

08

)

COMP

-

5

.

PROCEDURE

DIVISION

.

CALL

'cprog'

USING

VAL1

VAL2

INTTAB

BY

VALUE

ELEMENTS

PERFORM

VARYING

I

FROM

1

BY

1

UNTIL

I

50

DISPLAY

'I=:'

I

' VAL=:'

VAL

(

I

+

1

)

END

-

PERFORM

GOBACK

.

Just saying those uninitiated to COBOL should probably see COBOL from you :-)

---

how to pass in multiple values to a pointer using gnucobol to a c script please

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