std::ios_base::ios_base
From cppreference.com
| (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 std::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 stream buffer object and call std::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_baseobject before calling its init() was not clear |
the behavior is undefined in this case |
| LWG 1249 | C++98 | initialization did not need to be completed before first use | also needs to be completed |