std::basic_filebuf<CharT, Traits>* close();

If a put area exist (e.g. file was opened for writing), first calls overflow(Traits::eof()) to write all pending output to the file, including any unshift sequences.

If the most recently called function, out of underflow(), overflow(), seekpos(), and seekoff(), was overflow(), then calls std::codecvt::unshift(), perhaps multiple times, to determine the unshift sequence according to the imbued locale, and writes that sequence to file with overflow(Traits::eof()).

Then, closes the file as if by calling std::fclose(), regardless of whether any of the preceding calls succeeded or failed.

If any of the function calls made, including the call to std::fclose(), fails, returns a null pointer. If any of the function calls made throws an exception, the exception is caught and rethrown after closing the file. If the file is already closed, returns a null pointer right away.

In any case, updates the private member variable that is accessed by is_open().



Return value

this on success, a null pointer on failure.


close() is typically called through the destructor of std::basic_filebuf (which, in turn, is typically called by the destructor of std::basic_fstream.


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 443 C++98 the file was written using overflow(EOF) changed to overflow(Traits::eof())
LWG 622 C++98 it was unclear how to handle the
exception thrown during closing
it is rethrown after closing the file

See also

checks if the associated file is open
(public member function)
destructs a basic_filebuf object and closes the file if it is open
(virtual public member function)

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