Reference
C Library
IOstream Library
Strings library
STL Containers
STL Algorithms
Miscellaneous

IOstream Library
manipulators
classes:
filebuf
fstream
ifstream
ios
iostream
ios_base
istream
istringstream
ofstream
ostream
ostringstream
streambuf
stringbuf
stringstream
objects:
cerr
cin
clog
cout
types:
fpos
streamoff
streampos
streamsize

filebuf
filebuf::filebuf
filebuf::~filebuf
member functions:
filebuf::close
filebuf::is_open
filebuf::open
virtual members:
filebuf::imbue
filebuf::overflow
filebuf::pbackfail
filebuf::seekoff
filebuf::seekpos
filebuf::setbuf
filebuf::showmanyc
filebuf::sync
filebuf::uflow
filebuf::underflow

filebuf::underflow

virtual protected member function

int underflow ( );

Get character in the case of underflow

For the purpose of stream buffers, underflows happen when a new character is to be read at the get pointer gptr, but this has reached the end pointer egptr, indicating that apparently no more characters are available in the internal input array.

This function is expected to modify the eback, gptr and egptr pointers that define the internal input array in such a way that if there are more characters available in the controlled input sequence after the location represented by streambuf::egptr, at least some of them are made available through this internal input array and the new character available at the get pointer's position itself is returned. Otherwise, if there are no more characters available in the controlled input sequence after the one represented by egptr, the function returns EOF (or traits::eof() for other traits).

This member function overrides the inherited virtual member streambuf::underflow.

The behavior of this member function is similar to that of uflow except that the get pointer is not advanced.

Parameters

none

Return Value

The new character available at the get pointer position, if any. Otherwise, EOF (or traits::eof() for other traits) is returned.

Basic template member declaration

( basic_filebuf<charT,traits> )

1 2

typedef traits::int_type int_type;
int_type underflow ( );