无法访问在'std :: basic_ios< _Elem，_Traits>'中声明的私有成员 [英] Cannot access private member declared in class 'std::basic_ios<_Elem,_Traits>'

问题描述

这个特定方法有问题，不知道如何解决！我得到的错误是上述：

Having an issue with this particular method and not sure how to resolve it! The error I'm getting is the above:

错误C2248：'std :: basic_ios< _Elem，_Traits> :: basic_ios' ：can not
访问在类
中声明的私有成员std :: basic_ios< _Elem，_Traits>'C：\Program Files \Microsoft Visual
Studio 10.0 \VC\include\\ \\ strream 604

"error C2248: 'std::basic_ios<_Elem,_Traits>::basic_ios' : cannot access private member declared in class 'std::basic_ios<_Elem,_Traits>' C:\Program Files\Microsoft Visual Studio 10.0\VC\include\ostream 604"

我的方法是：

ostream operator<<( ostream & stream, ProcessClass const & rhs )
{
  stream << rhs.name_;
  return stream;
}

在标题中：

friend std::ostream operator<<( std::ostream & stream, ProcessClass const & rhs );

有关如何解决这个问题的任何想法？我认为这是通过引用传递而不是价值...但我有点困惑。

Any ideas on how to resolve this? I think it is something to do with passing by reference instead of value... but I'm a bit confused!

推荐答案

返回类型应为 ostream& ，它是对 ostream 的引用。

The return type should be ostream & which is a reference to ostream.

ostream & operator<<( ostream & stream, ProcessClass const & rhs )
{    //^^^ note this!
  stream << rhs.name_;
  return stream;
}

em> reference ），那么这需要复制流对象，但是通过使复制构造函数 sup> 1

When you return by value (instead of reference), then that requires copying of stream object, but copying of any stream object in C++ has been disabled by having made the copy-constructor¹ private.

¹

要知道为什么已停用任何流的复制，请在此处阅读我的详细答案：

To know why copying of any stream has been disabled, read my detail answer here:

• 为什么不允许复制字符串？

• Why copying stringstream is not allowed?

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