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_base
object 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 |