word_t *binarysearch(word_t *dict,char *str, int total)//二分查找，这是子程序
{
    //int index1;
    int mid, start = 0, end = total - 1;
    while(start <= end)
    {
        mid = (start + end) / 2;
        if(strcmp((dict+mid)->key, str) < 0)
            start = mid + 1;
        else if(strcmp((dict+mid)->key, str) > 0)
            end = mid - 1;
        else
            return dict+mid;
    }
    return NULL;
}将其变为递归，我该了一下一直是错误的，一直报错