char *my_str_cat(char* p_des, const char* p_src)
    {
        if (NULL == p_des || NULL == p_src)
        {
            return p_des;
        }
        char *p_des_head = p_des;
        while(*p_des)
        {
            p_des++;
        }
        while(*p_src)
        {
            *p_des = *p_src;
            p_des++;
            p_src++;
        }
        *p_des = '\0';

        return p_des_head;
    }