std::ios_base::ios_base(3)

NAME
std::ios_base::ios_base - std::ios_base::ios_base

Synopsis
   private: (until C++11)
   ios_base( const ios_base& );
   public: (1) (since C++11)
   ios_base( const ios_base& ) = delete;
   protected: (2)
   ios_base();
   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
                       the behavior of destroying a
   LWG 220 C++98 std::ios_base the behavior is
                       object before calling its init() was not undefined in this case
                       clear
   LWG 1249 C++98 initialization did not need to be also needs to be
                       completed before first use completed