std::basic_filebuf (3) - Linux Manuals

std::basic_filebuf: std::basic_filebuf

NAME

std::basic_filebuf - std::basic_filebuf

Synopsis

Defined in header <fstream>
template<
class CharT,
class Traits = std::char_traits<CharT>
> class basic_filebuf : public std::basic_streambuf<CharT, Traits>

std::basic_filebuf is a std::basic_streambuf whose associated character sequence is a file. Both the input sequence and the output sequence are associated with the same file, and a joint file position is maintained for both operations.
The functions underflow() and overflow()/sync() perform the actual I/O between the file and the get and put areas of the buffer. When CharT is not char, most implementations store multibyte characters in the file and a std::codecvt facet is used to perform wide/multibyte character conversion.
Two specializations for common character types are also defined:

Defined in header <streambuf>
Type Definition
filebuf basic_filebuf<char>
wfilebuf basic_filebuf<wchar_t>

Member types

Member type Definition
char_type CharT
traits_type Traits; the program is ill-formed if Traits::char_type is not CharT.
int_type Traits::int_type
pos_type Traits::pos_type which is required to be std::fpos<Traits::state_type>
off_type Traits::off_type

Member functions

Public member functions

              constructs a basic_filebuf object
constructor (public member function)

operator= assigns a basic_filebuf object
              (public member function)
(C++11)

swap swaps two basic_filebuf objects
              (public member function)
(C++11)

destructor destructs a basic_filebuf object and closes the file if it is open
              (virtual public member function)
[virtual]
              checks if the associated file is open
is_open (public member function)
              opens a file and configures it as the associated character sequence
open (public member function)
              flushes the put area buffer and closes the associated file
close (public member function)

Protected member functions

showmanyc optionally provides the number of characters available for input from the file
              (virtual protected member function)
[virtual]

underflow reads from the associated file
              (virtual protected member function)
[virtual]

uflow reads from the associated file and advances the next pointer in the get area
              (virtual protected member function)
[virtual]

pbackfail backs out the input sequence to unget a character, not affecting the associated file
              (virtual protected member function)
[virtual]

overflow writes characters to the associated file from the put area
              (virtual protected member function)
[virtual]

setbuf provides user-supplied buffer or turns this filebuf unbuffered
              (virtual protected member function)
[virtual]

seekoff repositions the file position, using relative addressing
              (virtual protected member function)
[virtual]

seekpos repositions the file position, using absolute addressing
              (virtual protected member function)
[virtual]

sync writes characters to the associated file from the put area
              (virtual protected member function)
[virtual]

imbue changes the associated locale
              (virtual protected member function)
[virtual]

Non-member functions

std::swap(std::basic_filebuf) specializes the std::swap algorithm
                              (function template)
(C++11)

Inherited from std::basic_streambuf

Member types

Member type Definition
char_type CharT
traits_type Traits; the program is ill-formed if Traits::char_type is not CharT.
int_type Traits::int_type
pos_type Traits::pos_type
off_type Traits::off_type

Member functions

destructor destructs the basic_streambuf object
                      (virtual public member function of std::basic_streambuf<CharT,Traits>)
[virtual]

Locales

                      invokes imbue()
pubimbue (public member function of std::basic_streambuf<CharT,Traits>)
                      obtains a copy of the associated locale
getloc (public member function of std::basic_streambuf<CharT,Traits>)

Positioning

                      invokes setbuf()
pubsetbuf (public member function of std::basic_streambuf<CharT,Traits>)
                      invokes seekoff()
pubseekoff (public member function of std::basic_streambuf<CharT,Traits>)
                      invokes seekpos()
pubseekpos (public member function of std::basic_streambuf<CharT,Traits>)
                      invokes sync()
pubsync (public member function of std::basic_streambuf<CharT,Traits>)

Get area

                      obtains the number of characters immediately available in the get area
in_avail (public member function of std::basic_streambuf<CharT,Traits>)
                      advances the input sequence, then reads one character without advancing again
snextc (public member function of std::basic_streambuf<CharT,Traits>)
                      reads one character from the input sequence and advances the sequence
sbumpc (public member function of std::basic_streambuf<CharT,Traits>)

stossc advances the input sequence as if by calling sbumpc() and discarding the result
                      (public member function)
(deprecated in C++98)
(removed in C++17)
                      reads one character from the input sequence without advancing the sequence
sgetc (public member function of std::basic_streambuf<CharT,Traits>)
                      invokes xsgetn()
sgetn (public member function of std::basic_streambuf<CharT,Traits>)

Put area

                      writes one character to the put area and advances the next pointer
sputc (public member function of std::basic_streambuf<CharT,Traits>)
                      invokes xsputn()
sputn (public member function of std::basic_streambuf<CharT,Traits>)

Putback

                      puts one character back in the input sequence
sputbackc (public member function of std::basic_streambuf<CharT,Traits>)
                      moves the next pointer in the input sequence back by one
sungetc (public member function of std::basic_streambuf<CharT,Traits>)

Protected member functions

              constructs a basic_streambuf object
constructor (protected member function)

operator= replaces a basic_streambuf object
              (protected member function)
(C++11)

swap swaps two basic_streambuf objects
              (protected member function)
(C++11)

Locales

imbue changes the associated locale
              (virtual protected member function of std::basic_streambuf<CharT,Traits>)
[virtual]

Positioning

setbuf replaces the buffer with user-defined array, if permitted
              (virtual protected member function of std::basic_streambuf<CharT,Traits>)
[virtual]

seekoff repositions the next pointer in the input sequence, output sequence, or both, using relative addressing
              (virtual protected member function of std::basic_streambuf<CharT,Traits>)
[virtual]

seekpos repositions the next pointer in the input sequence, output sequence, or both using absolute addressing
              (virtual protected member function of std::basic_streambuf<CharT,Traits>)
[virtual]

sync synchronizes the buffers with the associated character sequence
              (virtual protected member function of std::basic_streambuf<CharT,Traits>)
[virtual]

Get area

showmanyc obtains the number of characters available for input in the associated input sequence, if known
              (virtual protected member function of std::basic_streambuf<CharT,Traits>)
[virtual]

underflow reads characters from the associated input sequence to the get area
              (virtual protected member function of std::basic_streambuf<CharT,Traits>)
[virtual]

uflow reads characters from the associated input sequence to the get area and advances the next pointer
              (virtual protected member function of std::basic_streambuf<CharT,Traits>)
[virtual]

xsgetn reads multiple characters from the input sequence
              (virtual protected member function of std::basic_streambuf<CharT,Traits>)
[virtual]

eback returns a pointer to the beginning, current character and the end of the get area
gptr (protected member function)
egptr
              advances the next pointer in the input sequence
gbump (protected member function)
              repositions the beginning, next, and end pointers of the input sequence
setg (protected member function)

Put area

xsputn writes multiple characters to the output sequence
              (virtual protected member function of std::basic_streambuf<CharT,Traits>)
[virtual]

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

pbase returns a pointer to the beginning, current character and the end of the put area
pptr (protected member function)
epptr
              advances the next pointer of the output sequence
pbump (protected member function)
              repositions the beginning, next, and end pointers of the output sequence
setp (protected member function)

Putback

pbackfail puts a character back into the input sequence, possibly modifying the input sequence
              (virtual protected member function of std::basic_streambuf<CharT,Traits>)
[virtual]