二分搜索 float

Given a sorted array of floats, find the index of the number closest to x: Example: {1.2, 2.5, 9.3} x = 5, return 1

#include<iostream>
#include<stdlib.h>
#include <math.h>
using namespace std;

float a[] = {1.2, 2.6, 3.4, 4.2, 5.5, 6.7, 7.1, 8.5, 9.8, 9.9};

int main() 
{
    int n = sizeof(a)/sizeof(int);
    float f;
    cout << "Please input the number:" << endl;
    cin >> f;
    int low = 0;
    int high = n - 1;
    int mid;
    int index;
    float diff, diff_l, diff_r;
    while(low <= high) {
        int flag1 = 0;
        int flag2 = 0;
        mid = low + (high - low)/2;
        diff = (a[mid] - f) > 0 ? (a[mid] - f) : (f - a[mid]);
        if(mid - 1 >= low ) {
            diff_l = (a[mid - 1] - f) > 0 ? (a[mid - 1] - f) : (f -a[mid - 1]) ;
            flag1 = 1;
        }
        if(mid + 1 <= high){
            diff_r = (a[mid + 1] - f) > 0 ? (a[mid + 1] -f) : (f - a[mid + 1]);
            flag2 = 1;
        }
        if(flag1 == 1 && flag2 == 1)
        {
            if (diff_l >= diff && diff_r >= diff) {
                index = mid;
                break;
            } 
            if (diff_l < diff_r) {
                high = mid - 1;
            } else {
                low = mid + 1;
            }
        } else if(flag1 == 1) {
            if(diff_l >= diff) {
                index = mid ;
                break;
            } else {
                high = mid - 1;
            }
        } else if(flag2 == 1) {
            if (diff_r >= diff) {
                index = mid;
                break;
            } else {
                low = mid + 1;
            }
        } else {
            index  = mid;
            break;
        }
    }
    cout << index << endl;
    return 0;
}