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Problem when debugging piece of code while execution works

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skirby:
Hello,

As I don't know if it is the good place to post that but here is my problem.

When I debug this piece of code, I have the following error message:


If I click on Yes, here is what I have on the screen:


Otherwise, If I execute it directly, it works perfectly.


--- Code: ---#include <stdio.h>
#include <stdlib.h>

#define MAX 10

int main(void) {
  int i;
  unsigned char** s;
  s = (unsigned char**)malloc(MAX);
  if (s == NULL) {
    printf("Error allocating s\n");
    return -1;
  }

  for (i = 0; i < MAX; i++) {
    s[i] = (unsigned char*)malloc(MAX);

    if (s[i] == NULL)
      printf("Error allocating s[%d]\n", i);
    else
      sprintf((char*)s[i], "test %d", i);
  }

  for (i = 0; i < MAX; i++) {
    if (s[i] != NULL)
      printf("s[%d] : %s\n", i, s[i]);

    free(s[i]);
  }
  free(s);

  return 0;
}

--- End code ---

So, is my code wrong or is it a bug of the debugger?

Thanks and have a nice day.

sethjackson:
Well I really don't know, but umm this doesn't look good to me:


--- Code: (cpp) ---s[i] = (unsigned char*)malloc(MAX);

--- End code ---

when above you:


--- Code: (cpp) ---s = (unsigned char**)malloc(MAX);

--- End code ---

So generally if you get SIGSEV your code has a problem......

Game_Ender:
sethjackson, that is the proper way to dynamically allocate a 2 dimensional array in C.  From a single read through, your code looks correct skirby. I would bring up the stack trace window and see where the seg fault was triggered from.

EDIT: if thats straight C code you don't need the casts.

killerbot:
the code is WRONG :

there's a problem in the allocation of the array for the pointers, it has size of MAX bytes, which is 10.
It should be MAX * sizeof(unsigned char*).


Cheers

MortenMacFly:

--- Quote from: skirby on August 09, 2006, 05:42:37 pm ---When I debug this piece of code, I have the following error message:

--- End quote ---
Do you mind telling us the C::B/GDB versions you are using? At what line the debugger crashes? I can debug through this code just fine using revision 2829. I don't see any problem. Please try to be more descriptive, e.g. a step-by-step instrcution how to reproduce this crash.
With regards, Morten.

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