Difference between revisions of "cpp/io/basic filebuf"

Revision as of 01:30, 19 July 2020

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`[edit]
`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]

Member functions

Public member functions
(constructor)	constructs a `basic_filebuf` object (public member function) [edit]
operator= (C++11)	assigns a `basic_filebuf` object (public member function) [edit]
swap (C++11)	swaps two `basic_filebuf` objects (public member function) [edit]
(destructor) [virtual]	destructs a `basic_filebuf` object and closes the file if it is open (virtual public member function) [edit]
is_open	checks if the associated file is open (public member function) [edit]
open	opens a file and configures it as the associated character sequence (public member function) [edit]
close	flushes the put area buffer and closes the associated file (public member function) [edit]
Protected member functions
showmanyc [virtual]	optionally provides the number of characters available for input from the file (virtual protected member function) [edit]
underflow [virtual]	reads from the associated file (virtual protected member function) [edit]
uflow [virtual]	reads from the associated file and advances the next pointer in the get area (virtual protected member function) [edit]
pbackfail [virtual]	backs out the input sequence to unget a character, not affecting the associated file (virtual protected member function) [edit]
overflow [virtual]	writes characters to the associated file from the put area (virtual protected member function) [edit]
setbuf [virtual]	provides user-supplied buffer or turns this filebuf unbuffered (virtual protected member function) [edit]
seekoff [virtual]	repositions the file position, using relative addressing (virtual protected member function) [edit]
seekpos [virtual]	repositions the file position, using absolute addressing (virtual protected member function) [edit]
sync [virtual]	writes characters to the associated file from the put area (virtual protected member function) [edit]
imbue [virtual]	changes the associated locale (virtual protected member function) [edit]

Non-member functions

std::swap(std::basic_filebuf)

(C++11)

specializes the std::swap algorithm
(function template) [edit]

Inherited from std::basic_streambuf

Member types

Member type	Definition
`char_type`	`CharT`[edit]
`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

(destructor) [virtual]	destructs the `basic_streambuf` object (virtual public member function of `std::basic_streambuf<CharT,Traits>`) [edit]
Locales
pubimbue	invokes imbue() (public member function of `std::basic_streambuf<CharT,Traits>`) [edit]
getloc	obtains a copy of the associated locale (public member function of `std::basic_streambuf<CharT,Traits>`) [edit]
Positioning
pubsetbuf	invokes setbuf() (public member function of `std::basic_streambuf<CharT,Traits>`) [edit]
pubseekoff	invokes seekoff() (public member function of `std::basic_streambuf<CharT,Traits>`) [edit]
pubseekpos	invokes seekpos() (public member function of `std::basic_streambuf<CharT,Traits>`) [edit]
pubsync	invokes sync() (public member function of `std::basic_streambuf<CharT,Traits>`) [edit]
Get area
in_avail	obtains the number of characters immediately available in the get area (public member function of `std::basic_streambuf<CharT,Traits>`) [edit]
snextc	advances the input sequence, then reads one character without advancing again (public member function of `std::basic_streambuf<CharT,Traits>`) [edit]
sbumpcstossc (removed in C++17)	reads one character from the input sequence and advances the sequence (public member function of `std::basic_streambuf<CharT,Traits>`) [edit]
sgetc	reads one character from the input sequence without advancing the sequence (public member function of `std::basic_streambuf<CharT,Traits>`) [edit]
sgetn	invokes xsgetn() (public member function of `std::basic_streambuf<CharT,Traits>`) [edit]
Put area
sputc	writes one character to the put area and advances the next pointer (public member function of `std::basic_streambuf<CharT,Traits>`) [edit]
sputn	invokes xsputn() (public member function of `std::basic_streambuf<CharT,Traits>`) [edit]
Putback
sputbackc	puts one character back in the input sequence (public member function of `std::basic_streambuf<CharT,Traits>`) [edit]
sungetc	moves the next pointer in the input sequence back by one (public member function of `std::basic_streambuf<CharT,Traits>`) [edit]

Protected member functions

(constructor)	constructs a `basic_streambuf` object (protected member function) [edit]
operator= (C++11)	replaces a `basic_streambuf` object (protected member function) [edit]
swap (C++11)	swaps two `basic_streambuf` objects (protected member function) [edit]
Locales
imbue [virtual]	changes the associated locale (virtual protected member function of `std::basic_streambuf<CharT,Traits>`) [edit]
Positioning
setbuf [virtual]	replaces the buffer with user-defined array, if permitted (virtual protected member function of `std::basic_streambuf<CharT,Traits>`) [edit]
seekoff [virtual]	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]
seekpos [virtual]	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]
sync [virtual]	synchronizes the buffers with the associated character sequence (virtual protected member function of `std::basic_streambuf<CharT,Traits>`) [edit]
Get area
showmanyc [virtual]	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]
underflow [virtual]	reads characters from the associated input sequence to the get area (virtual protected member function of `std::basic_streambuf<CharT,Traits>`) [edit]
uflow [virtual]	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]
xsgetn [virtual]	reads multiple characters from the input sequence (virtual protected member function of `std::basic_streambuf<CharT,Traits>`) [edit]
ebackgptregptr	returns a pointer to the beginning, current character and the end of the get area (protected member function) [edit]
gbump	advances the next pointer in the input sequence (protected member function) [edit]
setg	repositions the beginning, next, and end pointers of the input sequence (protected member function) [edit]
Put area
xsputn [virtual]	writes multiple characters to the output sequence (virtual protected member function of `std::basic_streambuf<CharT,Traits>`) [edit]
overflow [virtual]	writes characters to the associated output sequence from the put area (virtual protected member function of `std::basic_streambuf<CharT,Traits>`) [edit]
pbasepptrepptr	returns a pointer to the beginning, current character and the end of the put area (protected member function) [edit]
pbump	advances the next pointer of the output sequence (protected member function) [edit]
setp	repositions the beginning, next, and end pointers of the output sequence (protected member function) [edit]
Putback
pbackfail [virtual]	puts a character back into the input sequence, possibly modifying the input sequence (virtual protected member function of `std::basic_streambuf<CharT,Traits>`) [edit]

@@ Line 62: / Line 62: @@
 {{cpp/io/basic_streambuf/inherit}}
-[[de:cpp/io/basic filebuf]]
+===See also===
-[[es:cpp/io/basic filebuf]]
+{{dsc begin}}
-[[fr:cpp/io/basic filebuf]]
+{{dsc inc | cpp/io/c/dsc FILE}}
-[[it:cpp/io/basic filebuf]]
+{{dsc end}}
-[[ja:cpp/io/basic filebuf]]
-[[pt:cpp/io/basic filebuf]]
+{{langlinks|de|es|fr|it|ja|pt|ru|zh}}
-[[ru:cpp/io/basic filebuf]]
-[[zh:cpp/io/basic filebuf]]

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basic_spanbuf (C++23)
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basic_osyncstream (C++20)
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Error category interface
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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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Difference between revisions of "cpp/io/basic filebuf"

Revision as of 01:30, 19 July 2020

Contents

Member types

Member functions

Public member functions

Protected member functions

Non-member functions

Inherited from std::basic_streambuf

Member types

Member functions

Locales

Positioning

Get area

Put area

Putback

Protected member functions

Locales

Positioning

Get area

Put area

Putback

See also

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