2 Step Sort

#include <stdio.h>
#include <stdlib.h>
static int compare(const void *p1, const void *p2) {
  for (int i = 0; i < 3; i++) {
    if (((double *)p1)[i] > ((double *)p2)[i]) return 1;
    else if (((double *)p1)[i] < ((double *)p2)[i]) return -1;
  }
  return 0;
}
int main(int ac, char **av) {
  double x[][3] = {
    { 1.0, 1.0, 1.0 },
    { 2.0, 5.0, 0.0 },
    { 2.0, 4.0, 1.0 },
    { 2.0, 3.0, 2.0 },
    { 2.0, 2.0, 3.0 },
    { 2.0, 1.0, 4.0 },
    { 1.0, 5.0, 0.0 },
    { 1.0, 4.0, 1.0 },
    { 1.0, 3.0, 2.0 },
    { 1.0, 2.0, 3.0 },
    { 1.0, 1.0, 4.0 },
    { 2.0, 2.0, 2.0 }
  };
  printf("Before:\n");
  for (int i = 0; i < sizeof(x) / sizeof(double *) / 3; i++) {
    printf("%2.1f, %2.1f, %2.1f\n", x[i][0], x[i][1], x[i][2]);
  }
  qsort(x, sizeof(x) / sizeof(double *) / 3, sizeof(x[0]), compare);
  printf("After:\n");
  for (int i = 0; i < sizeof(x) / sizeof(double *) / 3; i++) {
    printf("%2.1f, %2.1f, %2.1f\n", x[i][0], x[i][1], x[i][2]);
  }
}