W3cubDocs

std::ios_base::ios_base

	(1)
private: ios_base( const ios_base& );		(until C++11)
public: ios_base( const ios_base& ) = delete;		(since C++11)
protected: ios_base();	(2)

1) The copy constructor is private (until C++11)deleted (since C++11): streams are not copyable.

2) The default constructor is protected: only derived classes may construct std::ios_base. The internal state is undefined after the construction. The derived class must call basic_ios::init to complete initialization before first use or before destructor; otherwise the behavior is undefined.

Notes

The same applies to the constructors of the next class in the I/O hierarchy, std::basic_ios. Further-derived classes (std::istream and std::ostream) are always constructed with a concrete streambuffer object and call basic_ios::init(), possibly more than once, to complete initialization of their virtual base.

Defect reports

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 constructor was not specified	specified as private
LWG 220	C++98	the behavior of destroying a `std::ios_base` object before calling its `init()` was not clear	the behavior is undefined in this case

© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
https://en.cppreference.com/w/cpp/io/ios_base/ios_base