std::ios_base::operator= - cppreference.com

From cppreference.com

`private: ios_base& operator=( const ios_base& );`		(until C++11)
`public: ios_base& operator=( const ios_base& ) = delete;`		(since C++11)

The copy assignment operator is private(until C++11)deleted(since C++11): streams are not copy-assignable.

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR	Applied to	Behavior as published	Correct behavior
LWG 50	C++98	the copy assignment operator was not specified	specified as private