Binary Search

#include <stdio.h>
#include <stdlib.h>

int binarySearch(int *A, int n, int key) {
	int p = 0, q, r = (n-1);
	while (p < r) {
		q = (p + r) / 2;
		if (key == *(A + q)) {
			return q;
		}
		else if (key > *(A + q)) {
			p = q + 1;
		}
		else {
			r = q - 1;
		}
	}
	return -1;
}