二分法查找

假定输入数组已按递增序排序，查找整数x，代码如下：

int binary_search(int *array, int size, int x) {    int head = 0, tail = size - 1;    int mid;    while (head <= tail) {        mid = (head + tail) / 2;        if (array[mid] < x) {            head = mid + 1;        } else if (array[mid] > x) {            tail = mid - 1;        } else {            return mid;        }    }    return -1;}