# std::ios_base::ios_base

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< cpp‎ | io‎ | 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 `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

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