二分查找算法

int binary_search(int* a, int len,int goal)
{
int low=0;
int high= len-1;

while(low<= high)
{
int middle= (low+ high)/2;
if(a[middle]== goal)
return middle;
//在左半边
elseif(a[middle]> goal)
high = middle-1;
//在右半边
else
low = middle+1;
}

//没找到
return-1;
}