std::basic_filebuf<CharT,Traits>::overflow

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Input/output library

I/O manipulators
Print functions(C++23)
C-style I/O
Buffers
basic_streambuf
basic_filebuf
basic_stringbuf
basic_spanbuf (C++23)
strstreambuf (C++98/26*)
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ios_base
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basic_osyncstream (C++20)
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streamoff
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std::basic_filebuf

Public member functions
basic_filebuf::basic_filebuf
basic_filebuf::~basic_filebuf
basic_filebuf::operator= (C++11)
basic_filebuf::swap (C++11)
basic_filebuf::native_handle (C++26)
basic_filebuf::is_open
basic_filebuf::open
basic_filebuf::close
Protected member functions
basic_filebuf::showmanyc
basic_filebuf::underflow
basic_filebuf::uflow
basic_filebuf::pbackfail
basic_filebuf::overflow
basic_filebuf::setbuf
basic_filebuf::seekoff
basic_filebuf::seekpos
basic_filebuf::sync
basic_filebuf::imbue
Non-member functions
swap(std::basic_filebuf) (C++11)

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protected: virtual int_type overflow( int_type ch= Traits::eof());

Writes some data from the put area to the associated character sequence (to the file).

Behaves like the base class versionstd::basic_streambuf::overflow(), except that the behavior of “consuming characters” is defined as follows:

1) First, usesstd::codecvt::out of the imbued locale to convert the characters into external (possibly multibyte) representation, stored in a temporary buffer, as follows: (XSIZE is some unspecified buffer size)

conststd::codecvt<CharT,char,typename Traits::state_type>& a_codecvt=std::use_facet<std::codecvt<CharT,char,typename Traits::state_type>>(getloc());typename Traits::state_type state;CharT* end;char xbuf[XSIZE];char* xbuf_end;std::codecvt_base::result r=    a_codecvt.out(state, pbase(), pptr(), end, xbuf, xbuf+ XSIZE, xbuf_end);

2) Then writes all fully-converted characters from the buffer into the file. Formally, performs the following steps based on the value ofr:

r	Operation
std::codecvt_base::ok	Output characters in`[`xbuf`,` xbuf_end`)` to the file, and fail if output fails. At this point ifpbase()!= pptr() andpbase()== end are bothtrue (which meansxbuf is not large enough for even one external character), then increaseXSIZE and repeat from the beginning.
std::codecvt_base::partial	Output the converted external characters in`[`xbuf`,` xbuf_end`)` to the file, and repeat using the remaining unconverted internal characters in`[`end`,` pptr()`)`. If output fails, fail (without repeating).
std::codecvt_base::noconv	Output characters in`[`pbase()`,` pptr()`)` to the file.
std::codecvt_base::error	Fail.

If the associated file is not open (is_open() returnsfalse), output will always fail.

3) Establishes anobservable checkpoint.

(since C++26)

[edit]Parameters

the character to store in the put area

[edit]Return value

Traits::not_eof(ch) to indicate success orTraits::eof() to indicate failure.

[edit]Notes

Ifa_codecvt.always_noconv() returnstrue, the call toa_codecvt.out() may be skipped.

[edit]Example

This section is incomplete
Reason: no example

[edit]See also

overflow [virtual]	writes characters to the associated output sequence from the put area (virtual protected member function of`std::basic_streambuf<CharT,Traits>`)[edit]
underflow [virtual]	reads from the associated file (virtual protected member function)[edit]