bsearch.c 697 B

12345678910111213141516171819202122232425262728
  1. /*
  2. * (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
  3. * See the copyright notice in the ACK home directory, in the file "Copyright".
  4. */
  5. /* $Header$ */
  6. #include <stdlib.h>
  7. void *
  8. bsearch(register const void *key, register const void *base,
  9. register size_t nmemb, register size_t size,
  10. int (*compar)(const void *, const void *))
  11. {
  12. register const void *mid_point;
  13. register int cmp;
  14. while (nmemb > 0) {
  15. mid_point = (char *)base + size * (nmemb >> 1);
  16. if ((cmp = (*compar)(key, mid_point)) == 0)
  17. return (void *)mid_point;
  18. if (cmp >= 0) {
  19. base = (char *)mid_point + size;
  20. nmemb = (nmemb - 1) >> 1;
  21. } else
  22. nmemb >>= 1;
  23. }
  24. return (void *)NULL;
  25. }