c语言-二分查找法

二分查找法(有序情况下)

int bin_search(int arr[], int len, int key) {
	int mid = 0;
	int left = 0;
	int right = len - 1;
	while (left <= right) {
		mid = (left + right) / 2;
		if (key > arr[mid]) {
			left = mid + 1;
		}
		else if (key < arr[mid]) {
			right = mid - 1;
		}
		else {
			break;
		}
	}
	if (key == arr[mid]) {
		return mid;//找到则返回下标
	}
	else {
		return -1;//找不到返回-1
	}
}
int main() {
	int a[8] = { 1,3,4,6,23,45,67,89 };
	int len = sizeof(a) / sizeof(a[0]);
	int ret;
	ret = bin_search(a, len,22);
	printf("%d\n", ret);
	system("pause");
	return 0;
}