Thread: Big structure + file pointer = segmentation fault

Hi there,
I need to use a big structure (fixed size), with multiple file operations.
I could isolate the problem, contained inside the code below.

Code:

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <ctype.h>
#include <string.h>

typedef struct library59k { 
  int numModel;         
  char combination[6];  
  double rmsd_ext;		
  double rmsdTotal; 
  double det;
  double coord[28][3]; 
} lib; 

int main()
{

lib member[59049];

FILE *out;
	
	out = fopen("output", "w");
	if (out==NULL)
		{
		printf("cant write file.\n");
		exit(3);
		}
		
return 0;
}

The program compiles, but when I execute it, I get segmentation fault error, unless that I reduce the size of the structure.
Is there a size restriction for structures?
I guess it probably has to do with the size of the coord[28][3] pointer.
I'm using gcc 4.4 compiler.
thanks in advance for any help.

Local variables are instantiated on the stack, and most operating systems limit the amount of stack space available to a program. Try allocating from the heap instead (ie: malloc). Also, there are OS-specific API's that you can use to increase the size of the stack/heap.

I'm using Ubuntu 9.10. And yes, the code is exactly the same.
But I made the declaration global, and it worked great!
Next time I'll consider to dynamically alocate a big structure.
thanks a lot,

Juan Pablo

Originally Posted by zacs7

Considering you usually get 1-2MB, yes it is

Code:

zac@neux:~ (0) $ ulimit -s
8192

Make that 8KB...

As far as I know ulimit prints the stack size in kbytes, not bytes. So that would be 8MB.