std::basic_ios<CharT,Traits>::swap
Min standard notice:
Exchanges the states of *this and other, except for the associated rdbuf objects. rdbuf() and other.rdbuf() returns the same values as before the call.
# Declarations
protected:
void swap( basic_ios& other ) noexcept;
(since C++11)
# Parameters
other: the basic_ios object to exchange the state with