1  #include <execinfo.h>
       2  #include <inttypes.h>
       3  #include <stdio.h>
       4  #include <stdlib.h>
       5  #include <stdint.h>
       6  
       7  
       8  static int
       9  compare (const void *p1, const void *p2)
      10  {
      11    void *ba[20];
      12    int n = backtrace (ba, sizeof (ba) / sizeof (ba[0]));
      13    if (n != 0)
      14      {
      15        char **names = backtrace_symbols (ba, n);
      16        if (names != NULL)
      17  	{
      18  	  int i;
      19  	  printf ("called from %s\n", names[0]);
      20  	  for (i = 1; i < n; ++i)
      21  	    printf ("            %s\n", names[i]);
      22  	  free (names);
      23  	}
      24      }
      25  
      26    return *(const uint32_t *) p1 - *(const uint32_t *) p2;
      27  }
      28  
      29  
      30  int
      31  main (int argc, char *argv[])
      32  {
      33    uint32_t arr[20];
      34    size_t cnt;
      35  
      36    for (cnt = 0; cnt < sizeof (arr) / sizeof (arr[0]); ++cnt)
      37      arr[cnt] = random ();
      38  
      39    qsort (arr, sizeof (arr) / sizeof (arr[0]), sizeof (arr[0]), compare);
      40  
      41    for (cnt = 0; cnt < sizeof (arr) / sizeof (arr[0]); ++cnt)
      42      printf ("%" PRIx32 "\n", arr[cnt]);
      43  
      44    return 0;
      45  }