c return 出错。求解答

Question

感觉是不是我眼龊了哪里没看清楚，mid最后一次的值时2，然后return mid，result得到的却是1，为什么？

#include<stdio.h>

int binary_Search(int a[],int low,int high,int key){
    if(low>high) return -1;
    else{
        int mid=low+(high-low)/2;
        printf("low=%d,mid=%d,high=%d\n",low,mid,high);
        if(a[mid]==key) {
            printf("a[mid]=%d,mid=%d\n",a[mid],mid);
            return mid;
        }
        if(a[mid]<key)
            binary_Search(a,mid+1,high,key);
        if(a[mid]>key)
            binary_Search(a,low,mid-1,key);
    }
}


int main(){
    int a[]={0,1,2,3,4,5,6,7,9,10,11,12,13,14,15,16};
    int result;
    result=binary_Search(a,0,16,2);
    printf("result=%d\n",result);
    return 0;
}

Answer 1

很明显的错误嘛~
if(a[mid]key) return binary_Search(a,low,mid-1,key);