claude gave me the code to send strings back from C

[J McNamara]

Hi-

Looks like I will be getting a claude pro plan.

That was crazy. I can take strings and pass them into C and then get them back and display them appended based on what is passed in on the cobol end. That is what i was after. I will post the code when i get back from all the errands i have to run today.

THANKS everyone for being so patient.

jim

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[J McNamara]

Hi all-

Simon gave me a concise answer on another post - thank you Simon !
Here is a little longer answer i worked on with Claude.

This will allow you to take integer dat and append it to a buffer string. I am working on some plans to get the fields converted to char and then take char input like pic X(1024) and then pass them into C lang and get back the buffer that is appended.

You can see where I am headed with that logic. I can make a table from sql dat and pass it to whatever in Cobol.

Some dat types like 9(2) or 9(4) take up a certain length of bytes. I won't know if the field is 9(2) or 9(12). So I have to contend with that in my next plan I am devising with Claude AI.

It is not just integer dat but any dat I want to append to a char string in a buffer and get the results back.

i want to make a table viewer with cobjapi.

So here is what i have so far and how Claude helped me do it.
Working-Storage Section.
 01 BUFFER-AREA.          05 BUFFER-STRING    PIC X(200) VALUE SPACES.
          05 BUFFER-LEN      PIC S9(4) COMP-5 VALUE 200.
       01 VALUE-TO-ADD       PIC S9(4) COMP-5 VALUE 42.
       01 RETURN-PTR         USAGE POINTER
 MOVE "hello" TO BUFFER-STRING

Procedure Division.
              DISPLAY "Initial buffer: " BUFFER-STRING

*> Call C++ function
       CALL "accumulate_buffer"
           USING BY REFERENCE RETURN-PTR
                 BY REFERENCE BUFFER-STRING
                 BY REFERENCE VALUE-TO-ADD
                 BY REFERENCE BUFFER-LEN
       END-CALL

DISPLAY "After first call: " BUFFER-STRING

*> Try with second value
       MOVE 123 TO VALUE-TO-ADD
       CALL "accumulate_buffer"
           USING BY REFERENCE RETURN-PTR
                 BY REFERENCE BUFFER-STRING
                 BY REFERENCE VALUE-TO-ADD
                 BY REFERENCE BUFFER-LEN
       END-CALL

DISPLAY "After second call: " BUFFER-STRING

*> Test pointer dereferencing
       CALL "dereference_pointer"
           USING BY REFERENCE BUFFER-STRING
       END-CALL

If anyone wants how to make the DLL or the way to preprocess and compile please let me know.

Below is the C++ code Claude did almost all of it. It is so fast in C++ it isn't even funny.

I am very open with code that I am sharing at this point because the group has taught me several things and I am just a beginner.

thanks, 
jim

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

include <iostream></iostream>

using namespace std;

extern "C" {
    void dereference_pointer(char ptr) {
        std::cout << "Entering dereference_pointer" << std::endl;
        if (ptr != nullptr) {
            std::cout << "Value at the address: " << ptr << std::endl;
        } else {
            std::cout << "Null pointer received!" << std::endl;
        }
        std::cout << "Exiting dereference_pointer" << std::endl;
    }

char accumulate_buffer(char return_ptr, char buffer, int value, int size) {
        std::cout << "Entering accumulate_buffer" << std::endl;
        std::cout << "Raw buffer address: " << (void )buffer << std::endl;
        std::cout << "Raw value address: " << (void )value << std::endl;
        std::cout << "Raw size address: " << (void *)size << std::endl;

// Clean the buffer of newlines and unwanted characters
        for (int i = 0; i < *size; i++) {
            if (buffer[i] == '\n' || buffer[i] < ' ') {
                buffer[i] = '\0';
                break;
            }
        }

// Trim trailing spaces and nulls
        int actual_length = 0;
        while (actual_length < *size && buffer[actual_length] != '\0' && buffer[actual_length] != ' ') {
            actual_length++;
        }
        buffer[actual_length] = '\0';

std::cout << "Cleaned buffer: '" << buffer << "'" << std::endl;
        std::cout << "Actual length: " << actual_length << std::endl;
        std::cout << "value: " << (value ? value : -1) << std::endl;
        std::cout << "size: " << (size ? size : -1) << std::endl;

if (!buffer || !value || !size || size <= 0) {
            std::cerr << "Invalid input parameters!" << std::endl;
return_ptr = nullptr;
            return NULL;
        }

// Calculate space needed
        char temp[20];
        snprintf(temp, sizeof(temp), " %d", *value);
        int needed_space = actual_length + strlen(temp);  // Space for current content + new value

std::cout << "Space needed: " << needed_space << std::endl;

if (needed_space >= size) {
            std::cerr << "Buffer would overflow! Needed: " << needed_space << ", Have: " << size << std::endl;
            *return_ptr = nullptr;
            return NULL;
        }

// Append value with space prefix
        strcat(buffer, temp);

std::cout << "Final buffer: '" << buffer << "'" << std::endl;
return_ptr = buffer;
        return buffer;
    }
}
/
int main() {
    char buffer[100] = "hello";
    int size = 100;
    int value1 = 42;
    int value2 = 123;
    char* return_ptr = nullptr;

std::cout << "Initial buffer: " << buffer << std::endl;

// Test first value
    accumulate_buffer(&return_ptr, buffer, &value1, &size);
    std::cout << "After first call: " << buffer << std::endl;

// Test second value
    accumulate_buffer(&return_ptr, buffer, &value2, &size);
    std::cout << "After second call: " << buffer << std::endl;

// Test pointer dereferencing
    dereference_pointer(buffer);

return 0;
}
*/

Here is the output...
Starting cobsub.cblHERE
Initial buffer: hello

Entering accumulate_buffer
Raw buffer address: 0x7ff67aa9e080
Raw value address: 0x7ff67aa9e160
Raw size address: 0x7ff67aa9e148
Cleaned buffer: 'hello'
Actual length: 5
value: 42
size: 200
Space needed: 8
Final buffer: 'hello 42'
After first call: hello 42

Entering accumulate_buffer
Raw buffer address: 0x7ff67aa9e080
Raw value address: 0x7ff67aa9e160
Raw size address: 0x7ff67aa9e148
Cleaned buffer: 'hello'
Actual length: 5
value: 123
size: 200
Space needed: 9
Final buffer: 'hello 123'
After second call: hello 123

Entering dereference_pointer
Value at the address: h
Exiting dereference_pointer

[J McNamara]

Sorry the formatting of my elementary items and group level went kaflooey. It is all there, but I wish when I switched from rich to plain text it didn't do that. I am going to try to find the setting to make it default that it is plain text so it will stop hi-jacking the code formats.

thanks,
jim

[Simon Sobisch]

Best is to use the website (not mails) and surround all code by three backticks.

```c
C code highlighted 
```

```cobolfree
ADD 1 TO CODE
```

.. and if you answer by mail, consider Not including the old mail.