27 Input/output library [input.output]

27.5 Iostreams base classes [iostreams.base]

27.5.3 Class ios_base [ios.base]

27.5.3.7 ios_base constructors/destructor [ios.base.cons]

ios_base();

Effects: Each ios_base member has an indeterminate value after construction. The object's members shall be initialized by calling basic_ios::init before the object's first use or before it is destroyed, whichever comes first; otherwise the behavior is undefined.

~ios_base()

Effects: Destroys an object of class ios_base. Calls each registered callback pair (fn, index) ([ios.base.callback]) as (*fn)(erase_event, *this, index) at such time that any ios_base member function called from within fn has well defined results.