c语言问题，向各位请教

不是有题解吗，你照着看一遍，二分题有模板的

#include<stdio.h>
#include <iostream>
#include <vector>
using namespace std;
class Solution {
public :int search(vector<int>& nums, int target) {
        int low = 0, high = nums.size() - 1;
        while (low <= high) {
            int mid = (high - low) / 2 + low;
            int num = nums[mid];
            if (num == target) {
                return mid;
            }
            else if (num > target) {
                high = mid - 1;
            }
            else {
                low = mid + 1;
            }
        }
        return -1;
    }
};
 void main() {
        vector<int>nums = { 1,4,5,7,12,34,55 };
        int target = 7;
        Solution S ;
        int a = S.search(nums, target);
        cout << a << endl;
    }