1#include <stdlib.h>
 2
 3void *bsearch(const void *key, const void *base, size_t nel, size_t width, int (*cmp)(const void *, const void *))
 4{
 5	void *try;
 6	int sign;
 7	while (nel > 0) {
 8		try = (char *)base + width*(nel/2);
 9		sign = cmp(key, try);
10		if (sign < 0) {
11			nel /= 2;
12		} else if (sign > 0) {
13			base = (char *)try + width;
14			nel -= nel/2+1;
15		} else {
16			return try;
17		}
18	}
19	return NULL;
20}