摘要：
/** * @brief The quick-and-easy status check. * * This allows you to write constructs such as * "if (!a_stream) ..." and "while (a_stream) ..."*/operator void*() const{ return this->fail() ? 0 : const_cast<basic_ios*>(this); }如果你把一个basic_ios类的对象（cin就是）放到if语句的括号里，它就会被转换成v 阅读全文
