Input/output library
Buffers
Streams
Abstractions
File I/O
String I/O
Array I/O
Synchronized Output
Types
Error category interface
std::basic_filebuf
Public member functions
Protected member functions
Non-member functions
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 restrictions on reading and writing a sequence with std::basic_filebuf
are the same as std::FILE s.
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.
Several typedefs for common character types are provided:
Type
Definition
std::filebuf
std::basic_filebuf<char>
std::wfilebuf
std::basic_filebuf<wchar_t>
[edit] Member types
Type
Definition
traits_type
Traits
; the program is ill-formed if
Traits::char_type
is not
CharT
.
[edit]
int_type
Traits::int_type
[edit]
pos_type
Traits::pos_type
which is required to be
std::fpos <Traits::state_type>
off_type
Traits::off_type
[edit]
[edit] Member functions
Public member functions
constructs a
basic_filebuf
object
(public member function) [edit]
assigns a
basic_filebuf
object
(public member function) [edit]
swaps two
basic_filebuf
objects
(public member function) [edit]
returns the underlying implementation-defined handle
(public member function) [edit]
destructs a
basic_filebuf
object and closes the file if it is open
(virtual public member function) [edit]
checks if the associated file is open
(public member function) [edit]
opens a file and configures it as the associated character sequence
(public member function) [edit]
flushes the put area buffer and closes the associated file
(public member function) [edit]
Protected member functions
optionally provides the number of characters available for input from the file
(virtual protected member function) [edit]
reads from the associated file
(virtual protected member function) [edit]
reads from the associated file and advances the next pointer in the get area
(virtual protected member function) [edit]
backs out the input sequence to unget a character, not affecting the associated file
(virtual protected member function) [edit]
writes characters to the associated file from the put area
(virtual protected member function) [edit]
provides user-supplied buffer or turns this filebuf unbuffered
(virtual protected member function) [edit]
repositions the file position, using relative addressing
(virtual protected member function) [edit]
repositions the file position, using absolute addressing
(virtual protected member function) [edit]
writes characters to the associated file from the put area
(virtual protected member function) [edit]
changes the associated locale
(virtual protected member function) [edit]
[edit] Non-member functions
Member types
Member type
Definition
traits_type
Traits
; the program is ill-formed if
Traits::char_type
is not
CharT
.
[edit]
int_type
Traits::int_type
[edit]
pos_type
Traits::pos_type
[edit]
off_type
Traits::off_type
[edit]
Member functions
destructs the
basic_streambuf
object
(virtual public member function of std::basic_streambuf<CharT,Traits>
) [edit]
Locales
changes the associated locale and invokes
imbue() (public member function of std::basic_streambuf<CharT,Traits>
) [edit]
obtains a copy of the associated locale
(public member function of std::basic_streambuf<CharT,Traits>
) [edit]
Positioning
invokes
setbuf() (public member function of std::basic_streambuf<CharT,Traits>
) [edit]
invokes
seekoff() (public member function of std::basic_streambuf<CharT,Traits>
) [edit]
invokes
seekpos() (public member function of std::basic_streambuf<CharT,Traits>
) [edit]
invokes
sync() (public member function of std::basic_streambuf<CharT,Traits>
) [edit]
Get area
obtains the number of characters immediately available in the get area
(public member function of std::basic_streambuf<CharT,Traits>
) [edit]
advances the input sequence, then reads one character without advancing again
(public member function of std::basic_streambuf<CharT,Traits>
) [edit]
reads one character from the input sequence and advances the sequence
(public member function of std::basic_streambuf<CharT,Traits>
) [edit]
reads one character from the input sequence without advancing the sequence
(public member function of std::basic_streambuf<CharT,Traits>
) [edit]
invokes
xsgetn() (public member function of std::basic_streambuf<CharT,Traits>
) [edit]
Put area
writes one character to the put area and advances the next pointer
(public member function of std::basic_streambuf<CharT,Traits>
) [edit]
invokes
xsputn() (public member function of std::basic_streambuf<CharT,Traits>
) [edit]
Putback
puts one character back in the input sequence
(public member function of std::basic_streambuf<CharT,Traits>
) [edit]
moves the next pointer in the input sequence back by one
(public member function of std::basic_streambuf<CharT,Traits>
) [edit]
Protected member functions
constructs a
basic_streambuf
object
(protected member function) [edit]
replaces a
basic_streambuf
object
(protected member function) [edit]
swaps two
basic_streambuf
objects
(protected member function) [edit]
Locales
reacts to a change of the associated locale
(virtual protected member function of std::basic_streambuf<CharT,Traits>
) [edit]
Positioning
replaces the buffer with user-defined array, if permitted
(virtual protected member function of std::basic_streambuf<CharT,Traits>
) [edit]
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>
) [edit]
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>
) [edit]
synchronizes the buffers with the associated character sequence
(virtual protected member function of std::basic_streambuf<CharT,Traits>
) [edit]
Get area
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>
) [edit]
reads characters from the associated input sequence to the get area
(virtual protected member function of std::basic_streambuf<CharT,Traits>
) [edit]
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>
) [edit]
reads multiple characters from the input sequence
(virtual protected member function of std::basic_streambuf<CharT,Traits>
) [edit]
returns a pointer to the beginning, current character and the end of the get area
(protected member function) [edit]
advances the next pointer in the input sequence
(protected member function) [edit]
repositions the beginning, next, and end pointers of the input sequence
(protected member function) [edit]
Put area
writes multiple characters to the output sequence
(virtual protected member function of std::basic_streambuf<CharT,Traits>
) [edit]
writes characters to the associated output sequence from the put area
(virtual protected member function of std::basic_streambuf<CharT,Traits>
) [edit]
returns a pointer to the beginning, current character and the end of the put area
(protected member function) [edit]
advances the next pointer of the output sequence
(protected member function) [edit]
repositions the beginning, next, and end pointers of the output sequence
(protected member function) [edit]
Putback
puts a character back into the input sequence, possibly modifying the input sequence
(virtual protected member function of std::basic_streambuf<CharT,Traits>
) [edit]
[edit] See also
object type, capable of holding all information needed to control a C I/O stream
(typedef) [edit]