相关疑难解决方法(0)

我在这个二进制搜索算法上遇到了奇怪的编译器错误.我收到警告control reaches end of non-void function.这是什么意思？

int binary(int val, int sorted[], int low, int high) {
    int mid = (low+high)/2;

    if(high < low)
        return -1;

    if(val < sorted[mid])
        return binary(val, sorted, low, mid-1);

    else if(val > sorted[mid])
        return binary(val, sorted, mid+1, high);

    else if(val == sorted[mid])
        return mid;
}