index of array with its value...

gistfile1.txt

int  index_search(int x[], int n) {
	int  first = 0;
	int  last  = n - 1;
	int  middle, index;

	index = -1;
	while (first <= last) {  /* a modified binary search*/
		middle = (first + last) / 2;
		if (x[middle] == middle) {
			index = middle;
			break;
		} else if (x[middle] > middle) {
			last = middle - 1;
		} else {
			first = middle + 1;
		}
	}
	return index;
}