#include <stdio.h>
struct my_struct {
     int a, b;
};
int
sort_cb(const void *d1, const void *d2)
{
   const struct my_struct *x1, *x2;
   l1 = d1;
   l2 = d2;
   return x1->a - x2->a;
}
int
main(void)
{
   struct my_struct *d, *cur;
   d = malloc(sizeof(*d));
   d->a = 1;
   d->b = 10;
   d = malloc(sizeof(*d));
   d->a = 2;
   d->b = 20;
   d = malloc(sizeof(*d));
   d->a = 3;
   d->b = 30;
   printf("list=%p\n", list);
     printf("\ta=%d, b=%d\n", cur->a, cur->b);
   d = malloc(sizeof(*d));
   d->a = 4;
   d->b = 40;
   printf("list after sort=%p\n", list);
     printf("\ta=%d, b=%d\n", cur->a, cur->b);
   if (tmp)
   else
     cur = NULL;
   if (d != cur)
     printf("wrong node! cur=%p\n", cur);
   free(d);
   printf("list=%p\n", list);
   for (itr = list; itr != NULL; itr = itr->
next)
      {
        printf("\ta=%d, b=%d\n", cur->a, cur->b);
     }
   while (list)
     {
                                                          struct my_struct);
        free(aux);
     }
   return 0;
}