# std::basic_filebuf< _CharT, _Traits > Class Template Reference

Inheritance diagram for std::basic_filebuf< _CharT, _Traits >:

List of all members.

## Detailed Description

### template<typename _CharT, typename _Traits>
class std::basic_filebuf< _CharT, _Traits >

This class associates both its input and output sequence with an external disk file, and maintains a joint file position for both sequences. Many of its sematics are described in terms of similar behavior in the Standard C Library's `FILE` streams.

Definition at line 69 of file fstream.

- locale _M_buf_locale
- char_type * _M_in_beg
- char_type * _M_in_cur
- char_type * _M_in_end
- char_type * _M_out_beg
- char_type * _M_out_cur
- char_type * _M_out_end
- locale getloc () const
- locale pubimbue (const locale &__loc)
- pos_type pubseekoff (off_type __off, ios_base::seekdir __way, ios_base::openmode __mode=ios_base::in|ios_base::out)
- pos_type pubseekpos (pos_type __sp, ios_base::openmode __mode=ios_base::in|ios_base::out)
- __streambuf_type * pubsetbuf (char_type *__s, streamsize __n)
- int pubsync ()

## Public Types

- typedef codecvt< char_type,
  char, __state_type > __codecvt_type
- typedef __basic_file< char > __file_type
- typedef basic_filebuf< char_type,
  traits_type > __filebuf_type
- typedef traits_type::state_type __state_type
- typedef basic_streambuf< char_type,
  traits_type > __streambuf_type
- typedef _CharT char_type
- typedef traits_type::int_type int_type
- typedef traits_type::off_type off_type
- typedef traits_type::pos_type pos_type
- typedef _Traits traits_type

## Public Member Functions

- basic_filebuf ()
- __filebuf_type * close () throw ()
- streamsize in_avail ()
- bool is_open () const throw ()
- __filebuf_type * open (const char *__s, ios_base::openmode __mode)
- int_type sbumpc ()
- int_type sgetc ()
- streamsize sgetn (char_type *__s, streamsize __n)
- int_type snextc ()
- int_type sputbackc (char_type __c)
- int_type sputc (char_type __c)
- streamsize sputn (const char_type *__s, streamsize __n)
- void stossc ()
- int_type sungetc ()
- virtual ~basic_filebuf ()

## Protected Member Functions

- void _M_allocate_internal_buffer ()
- bool _M_convert_to_external (char_type *, streamsize)
- void _M_create_pback ()
- void _M_destroy_internal_buffer () throw ()
- void _M_destroy_pback () throw ()
- pos_type _M_seek (off_type __off, ios_base::seekdir __way, __state_type __state)
- void _M_set_buffer (streamsize __off)
- bool _M_terminate_output ()
- void gbump (int __n)
- virtual void imbue (const locale &__loc)
- virtual int_type overflow (int_type __c=_Traits::eof())
- virtual int_type pbackfail (int_type __c=_Traits::eof())
- void pbump (int __n)
- virtual pos_type seekoff (off_type __off, ios_base::seekdir __way, ios_base::openmode __mode=ios_base::in|ios_base::out)
- virtual pos_type seekpos (pos_type __pos, ios_base::openmode __mode=ios_base::in|ios_base::out)
- virtual __streambuf_type * setbuf (char_type *__s, streamsize __n)
- void setg (char_type *__gbeg, char_type *__gnext, char_type *__gend)
- void setp (char_type *__pbeg, char_type *__pend)
- virtual streamsize showmanyc ()
- virtual int sync ()
- virtual int_type uflow ()
- virtual int_type underflow ()
- virtual streamsize xsgetn (char_type *__s, streamsize __n)
- virtual streamsize xsputn (const char_type *__s, streamsize __n)

- char_type * eback () const
- char_type * egptr () const
- char_type * gptr () const

- char_type * epptr () const
- char_type * pbase () const
- char_type * pptr () const

## Protected Attributes

- char_type * _M_buf
- bool _M_buf_allocated
- size_t _M_buf_size
- const __codecvt_type * _M_codecvt
- char * _M_ext_buf
- streamsize _M_ext_buf_size
- char * _M_ext_end
- const char * _M_ext_next
- __file_type _M_file
- __c_lock _M_lock
- ios_base::openmode _M_mode
- bool _M_reading
- __state_type _M_state_beg
- __state_type _M_state_cur
- __state_type _M_state_last
- bool _M_writing

- char_type _M_pback
- char_type * _M_pback_cur_save
- char_type * _M_pback_end_save
- bool _M_pback_init

## Friends

- template<typename _CharT2> __gnu_cxx::__enable_if< __is_char<
  _CharT2 >::__value, _CharT2
  * >::__type __copy_aux (istreambuf_iterator< _CharT2 >, istreambuf_iterator< _CharT2 >, _CharT2 *)
- streamsize __copy_streambufs_eof (__streambuf_type *, __streambuf_type *, bool &)
- class basic_ios< char_type, traits_type >
- class basic_istream< char_type, traits_type >
- class basic_ostream< char_type, traits_type >
- template<typename _CharT2> __gnu_cxx::__enable_if< __is_char<
  _CharT2 >::__value, istreambuf_iterator<
  _CharT2 > >::__type find (istreambuf_iterator< _CharT2 >, istreambuf_iterator< _CharT2 >, const _CharT2 &)
- template<typename _CharT2, typename _Traits2, typename _Alloc> basic_istream< _CharT2, _Traits2 > & getline (basic_istream< _CharT2, _Traits2 > &, basic_string< _CharT2, _Traits2, _Alloc > &, _CharT2)
- class ios_base
- class istreambuf_iterator< char_type, traits_type >
- template<typename _CharT2, typename _Traits2, typename _Alloc> basic_istream< _CharT2, _Traits2 > & operator>> (basic_istream< _CharT2, _Traits2 > &, basic_string< _CharT2, _Traits2, _Alloc > &)
- template<typename _CharT2, typename _Traits2> basic_istream< _CharT2, _Traits2 > & operator>> (basic_istream< _CharT2, _Traits2 > &, _CharT2 *)
- class ostreambuf_iterator< char_type, traits_type >

## Member Typedef Documentation

template<typename _CharT, typename _Traits>

typedef _CharT std::basic_filebuf< _CharT, _Traits >::char_type

These are standard types. They permit a standardized way of referring to names of (or names dependant on) the template parameters, which are specific to the implementation.

Reimplemented from std::basic_streambuf< _CharT, _Traits >.

Reimplemented in __gnu_cxx::stdio_filebuf< _CharT, _Traits >.

Definition at line 73 of file fstream.

template<typename _CharT, typename _Traits>

typedef traits_type::int_type std::basic_filebuf< _CharT, _Traits >::int_type

These are standard types. They permit a standardized way of referring to names of (or names dependant on) the template parameters, which are specific to the implementation.

Reimplemented from std::basic_streambuf< _CharT, _Traits >.

Reimplemented in __gnu_cxx::stdio_filebuf< _CharT, _Traits >.

Definition at line 75 of file fstream.

template<typename _CharT, typename _Traits>

typedef traits_type::off_type std::basic_filebuf< _CharT, _Traits >::off_type

These are standard types. They permit a standardized way of referring to names of (or names dependant on) the template parameters, which are specific to the implementation.

Reimplemented from std::basic_streambuf< _CharT, _Traits >.

Reimplemented in __gnu_cxx::stdio_filebuf< _CharT, _Traits >.

Definition at line 77 of file fstream.

template<typename _CharT, typename _Traits>

typedef traits_type::pos_type std::basic_filebuf< _CharT, _Traits >::pos_type

These are standard types. They permit a standardized way of referring to names of (or names dependant on) the template parameters, which are specific to the implementation.

Reimplemented from std::basic_streambuf< _CharT, _Traits >.

Reimplemented in __gnu_cxx::stdio_filebuf< _CharT, _Traits >.

Definition at line 76 of file fstream.

template<typename _CharT, typename _Traits>

typedef _Traits std::basic_filebuf< _CharT, _Traits >::traits_type

These are standard types. They permit a standardized way of referring to names of (or names dependant on) the template parameters, which are specific to the implementation.

Reimplemented from std::basic_streambuf< _CharT, _Traits >.

Reimplemented in __gnu_cxx::stdio_filebuf< _CharT, _Traits >.

Definition at line 74 of file fstream.

## Constructor & Destructor Documentation

template<typename _CharT, typename _Traits>

std::basic_filebuf< _CharT, _Traits >::basic_filebuf | ( |  | ) |

Does not open any files.

The default constructor initializes the parent class using its own default ctor.

Definition at line 81 of file fstream.tcc.

References std::basic_streambuf< _CharT, _Traits >::_M_buf_locale, and std::basic_filebuf< _CharT, _Traits >::_M_codecvt.

template<typename _CharT, typename _Traits>

virtual std::basic_filebuf< _CharT, _Traits >::~basic_filebuf | ( |  | ) | `[inline, virtual]`

The destructor closes the file first.

Definition at line 240 of file fstream.

## Member Function Documentation

template<typename _CharT, typename _Traits>

basic_filebuf< _CharT, _Traits >::__filebuf_type * std::basic_filebuf< _CharT, _Traits >::close | ( |  | ) | throw ()

Closes the currently associated file.

Returns:
  `this` on success, NULL on failure

If no file is currently open, this function immediately fails.

If a "put buffer area" exists, `overflow(eof)` is called to flush all the characters. The file is then closed.

If any operations fail, this function also fails.

Definition at line 130 of file fstream.tcc.

References std::basic_filebuf< _CharT, _Traits >::_M_destroy_internal_buffer(), std::basic_filebuf< _CharT, _Traits >::_M_file, std::basic_filebuf< _CharT, _Traits >::_M_mode, std::basic_filebuf< _CharT, _Traits >::_M_pback_init, std::basic_filebuf< _CharT, _Traits >::_M_reading, std::basic_filebuf< _CharT, _Traits >::_M_set_buffer(), std::basic_filebuf< _CharT, _Traits >::_M_state_beg, std::basic_filebuf< _CharT, _Traits >::_M_state_cur, std::basic_filebuf< _CharT, _Traits >::_M_state_last, std::basic_filebuf< _CharT, _Traits >::_M_terminate_output(), std::basic_filebuf< _CharT, _Traits >::_M_writing, and std::__basic_file< char >::close().

template<typename _CharT, typename _Traits>

char_type* std::basic_streambuf< _CharT, _Traits >::eback | ( |  | ) | const`[inline, protected, inherited]`

Access to the get area.

These functions are only available to other protected functions, including derived classes.

- eback() returns the beginning pointer for the input sequence
- gptr() returns the next pointer for the input sequence
- egptr() returns the end pointer for the input sequence

Definition at line 478 of file streambuf.

Referenced by std::basic_filebuf< _CharT, _Traits >::imbue(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::overflow(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::seekoff(), std::basic_filebuf< _CharT, _Traits >::seekoff(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::seekpos(), std::basic_filebuf< _CharT, _Traits >::underflow(), and std::basic_filebuf< _CharT, _Traits >::xsgetn().

template<typename _CharT, typename _Traits>

char_type* std::basic_streambuf< _CharT, _Traits >::egptr | ( |  | ) | const`[inline, protected, inherited]`

Access to the get area.

These functions are only available to other protected functions, including derived classes.

- eback() returns the beginning pointer for the input sequence
- gptr() returns the next pointer for the input sequence
- egptr() returns the end pointer for the input sequence

Definition at line 484 of file streambuf.

Referenced by std::basic_stringbuf< _CharT, _Traits, _Alloc >::seekoff(), std::basic_filebuf< _CharT, _Traits >::seekoff(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::seekpos(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::underflow(), std::basic_filebuf< _CharT, _Traits >::underflow(), and std::basic_filebuf< _CharT, _Traits >::xsgetn().

template<typename _CharT, typename _Traits>

void std::basic_streambuf< _CharT, _Traits >::gbump | ( | int | __n | ) | `[inline, protected, inherited]`

Moving the read position.

Parameters:

  | n | The delta by which to move.

This just advances the read position without returning any data.

Definition at line 494 of file streambuf.

Referenced by std::basic_stringbuf< _CharT, _Traits, _Alloc >::seekpos(), and std::basic_filebuf< _CharT, _Traits >::xsgetn().

template<typename _CharT, typename _Traits>

locale std::basic_streambuf< _CharT, _Traits >::getloc | ( |  | ) | const`[inline, inherited]`

Locale access.

Returns:
  The current locale in effect.

If pubimbue(loc) has been called, then the most recent `loc` is returned. Otherwise the global locale in effect at the time of construction is returned.

Definition at line 241 of file streambuf.

template<typename _CharT, typename _Traits>

char_type* std::basic_streambuf< _CharT, _Traits >::gptr | ( |  | ) | const`[inline, protected, inherited]`

Access to the get area.

These functions are only available to other protected functions, including derived classes.

- eback() returns the beginning pointer for the input sequence
- gptr() returns the next pointer for the input sequence
- egptr() returns the end pointer for the input sequence

Definition at line 481 of file streambuf.

Referenced by std::basic_filebuf< _CharT, _Traits >::pbackfail(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::seekoff(), std::basic_filebuf< _CharT, _Traits >::showmanyc(), and std::basic_filebuf< _CharT, _Traits >::xsgetn().

template<typename _CharT, typename _Traits>

void std::basic_filebuf< _CharT, _Traits >::imbue | ( | const locale & | __loc | ) | `[protected, virtual]`

Changes translations.

Parameters:

  | loc | A new locale.

Translations done during I/O which depend on the current locale are changed by this call. The standard adds, "Between invocations of this function a class derived from streambuf can safely cache results of calls to locale functions and to members of facets so obtained."

Note:
  Base class version does nothing.

Reimplemented from std::basic_streambuf< _CharT, _Traits >.

Definition at line 837 of file fstream.tcc.

References std::__check_facet(), std::basic_filebuf< _CharT, _Traits >::_M_codecvt, std::basic_filebuf< _CharT, _Traits >::_M_ext_buf, std::basic_filebuf< _CharT, _Traits >::_M_ext_end, std::basic_filebuf< _CharT, _Traits >::_M_ext_next, std::basic_filebuf< _CharT, _Traits >::_M_mode, std::basic_filebuf< _CharT, _Traits >::_M_reading, std::basic_filebuf< _CharT, _Traits >::_M_set_buffer(), std::basic_filebuf< _CharT, _Traits >::_M_state_beg, std::basic_filebuf< _CharT, _Traits >::_M_state_cur, std::basic_filebuf< _CharT, _Traits >::_M_state_last, std::basic_filebuf< _CharT, _Traits >::_M_terminate_output(), std::basic_filebuf< _CharT, _Traits >::_M_writing, std::ios_base::cur, std::basic_streambuf< _CharT, _Traits >::eback(), and std::basic_filebuf< _CharT, _Traits >::seekoff().

template<typename _CharT, typename _Traits>

streamsize std::basic_streambuf< _CharT, _Traits >::in_avail | ( |  | ) | `[inline, inherited]`

Looking ahead into the stream.

Returns:
  The number of characters available.

If a read position is available, returns the number of characters available for reading before the buffer must be refilled. Otherwise returns the derived `showmanyc()`.

Definition at line 281 of file streambuf.

template<typename _CharT, typename _Traits>

bool std::basic_filebuf< _CharT, _Traits >::is_open | ( |  | ) | const throw ()`[inline]`

Returns true if the external file is open.

Definition at line 248 of file fstream.

References std::__basic_file< char >::is_open().

template<typename _CharT, typename _Traits>

basic_filebuf< _CharT, _Traits >::__filebuf_type * std::basic_filebuf< _CharT, _Traits >::open | ( | const char * | __s,
|  | ios_base::openmode | __mode |
| ) |  |  |

Opens an external file.

Parameters:

  | s | The name of the file.
  | mode | The open mode flags.

Returns:
  `this` on success, NULL on failure

If a file is already open, this function immediately fails. Otherwise it tries to open the file named s using the flags given in mode.

Table 92, adapted here, gives the relation between openmode combinations and the equivalent fopen() flags. (NB: lines in|out|app and binary|in|out|app per DR 596) +---------------------------------------------------------+ | ios_base Flag combination stdio equivalent | |binary in out trunc app | +---------------------------------------------------------+ | + "w" | | + + "a" | | + + "w" | | + "r" | | + + "r+" | | + + + "w+" | | + + + "a+" | +---------------------------------------------------------+ | + + "wb" | | + + + "ab" | | + + + "wb" | | + + "rb" | | + + + "r+b" | | + + + + "w+b" | | + + + + "a+b" | +---------------------------------------------------------+

Definition at line 96 of file fstream.tcc.

References std::basic_filebuf< _CharT, _Traits >::_M_allocate_internal_buffer(), std::basic_filebuf< _CharT, _Traits >::_M_file, std::basic_filebuf< _CharT, _Traits >::_M_mode, std::basic_filebuf< _CharT, _Traits >::_M_reading, std::basic_filebuf< _CharT, _Traits >::_M_set_buffer(), std::basic_filebuf< _CharT, _Traits >::_M_state_beg, std::basic_filebuf< _CharT, _Traits >::_M_state_cur, std::basic_filebuf< _CharT, _Traits >::_M_state_last, std::basic_filebuf< _CharT, _Traits >::_M_writing, std::ios_base::ate, std::ios_base::end, and std::__basic_file< char >::open().

template<typename _CharT, typename _Traits>

basic_filebuf< _CharT, _Traits >::int_type std::basic_filebuf< _CharT, _Traits >::overflow | ( | int_type | __c = `_Traits::eof()` | ) | `[protected, virtual]`

Consumes data from the buffer; writes to the controlled sequence.

Parameters:

  | c | An additional character to consume.

Returns:
  eof() to indicate failure, something else (usually c, or not_eof())

Informally, this function is called when the output buffer is full (or does not exist, as buffering need not actually be done). If a buffer exists, it is "consumed", with "some effect" on the controlled sequence. (Typically, the buffer is written out to the sequence verbatim.) In either case, the character c is also written out, if c is not `eof()`.

For a formal definiton of this function, see a good text such as Langer & Kreft, or [27.5.2.4.5]/3-7.

A functioning output streambuf can be created by overriding only this function (no buffer area will be used).

Note:
  Base class version does nothing, returns eof().

Reimplemented from std::basic_streambuf< _CharT, _Traits >.

Definition at line 392 of file fstream.tcc.

References std::basic_filebuf< _CharT, _Traits >::_M_buf_size, std::basic_filebuf< _CharT, _Traits >::_M_convert_to_external(), std::basic_filebuf< _CharT, _Traits >::_M_mode, std::basic_filebuf< _CharT, _Traits >::_M_reading, std::basic_filebuf< _CharT, _Traits >::_M_set_buffer(), std::basic_filebuf< _CharT, _Traits >::_M_writing, std::ios_base::out, std::basic_streambuf< _CharT, _Traits >::pbase(), std::basic_streambuf< _CharT, _Traits >::pbump(), and std::basic_streambuf< _CharT, _Traits >::pptr().

Referenced by std::basic_filebuf< _CharT, _Traits >::_M_terminate_output().

template<typename _CharT, typename _Traits>

basic_filebuf< _CharT, _Traits >::int_type std::basic_filebuf< _CharT, _Traits >::pbackfail | ( | int_type | __c = `_Traits::eof()` | ) | `[protected, virtual]`

Tries to back up the input sequence.

Parameters:

  | c | The character to be inserted back into the sequence.

Returns:
  eof() on failure, "some other value" on success

Postcondition:
  The constraints of `gptr()`, `eback()`, and `pptr()` are the same as for `underflow()`.

Note:
  Base class version does nothing, returns eof().

Reimplemented from std::basic_streambuf< _CharT, _Traits >.

Definition at line 340 of file fstream.tcc.

References std::basic_filebuf< _CharT, _Traits >::_M_create_pback(), std::basic_filebuf< _CharT, _Traits >::_M_mode, std::basic_filebuf< _CharT, _Traits >::_M_pback_init, std::basic_filebuf< _CharT, _Traits >::_M_reading, std::basic_filebuf< _CharT, _Traits >::_M_writing, std::ios_base::cur, std::basic_streambuf< _CharT, _Traits >::gptr(), and std::ios_base::in.

template<typename _CharT, typename _Traits>

char_type* std::basic_streambuf< _CharT, _Traits >::pbase | ( |  | ) | const`[inline, protected, inherited]`

Access to the put area.

These functions are only available to other protected functions, including derived classes.

- pbase() returns the beginning pointer for the output sequence
- pptr() returns the next pointer for the output sequence
- epptr() returns the end pointer for the output sequence

Definition at line 525 of file streambuf.

Referenced by std::basic_stringbuf< _CharT, _Traits, _Alloc >::overflow(), std::basic_filebuf< _CharT, _Traits >::overflow(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::seekoff(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::seekpos(), and std::basic_filebuf< _CharT, _Traits >::xsputn().

template<typename _CharT, typename _Traits>

void std::basic_streambuf< _CharT, _Traits >::pbump | ( | int | __n | ) | `[inline, protected, inherited]`

Moving the write position.

Parameters:

  | n | The delta by which to move.

This just advances the write position without returning any data.

Definition at line 541 of file streambuf.

Referenced by std::basic_stringbuf< _CharT, _Traits, _Alloc >::_M_sync(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::overflow(), std::basic_filebuf< _CharT, _Traits >::overflow(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::seekpos(), and std::basic_streambuf< _CharT, _Traits >::xsputn().

template<typename _CharT, typename _Traits>

locale std::basic_streambuf< _CharT, _Traits >::pubimbue | ( | const locale & | __loc | ) | `[inline, inherited]`

Entry point for imbue().

Parameters:

  | loc | The new locale.

Returns:
  The previous locale.

Calls the derived imbue(loc).

Definition at line 224 of file streambuf.

template<typename _CharT, typename _Traits>

pos_type std::basic_streambuf< _CharT, _Traits >::pubseekoff | ( | off_type | __off,
|  | ios_base::seekdir | __way,
|  | ios_base::openmode | __mode = `ios_base::in | ios_base::out` |
| ) |  |  | `[inline, inherited]`

Locale access.

Returns:
  The current locale in effect.

If pubimbue(loc) has been called, then the most recent `loc` is returned. Otherwise the global locale in effect at the time of construction is returned.

Definition at line 258 of file streambuf.

template<typename _CharT, typename _Traits>

pos_type std::basic_streambuf< _CharT, _Traits >::pubseekpos | ( | pos_type | __sp,
|  | ios_base::openmode | __mode = `ios_base::in | ios_base::out` |
| ) |  |  | `[inline, inherited]`

Locale access.

Returns:
  The current locale in effect.

If pubimbue(loc) has been called, then the most recent `loc` is returned. Otherwise the global locale in effect at the time of construction is returned.

Definition at line 263 of file streambuf.

template<typename _CharT, typename _Traits>

__streambuf_type* std::basic_streambuf< _CharT, _Traits >::pubsetbuf | ( | char_type * | __s,
|  | streamsize | __n |
| ) |  |  | `[inline, inherited]`

Entry points for derived buffer functions.

The public versions of `pubfoo` dispatch to the protected derived `foo` member functions, passing the arguments (if any) and returning the result unchanged.

Definition at line 254 of file streambuf.

template<typename _CharT, typename _Traits>

int std::basic_streambuf< _CharT, _Traits >::pubsync | ( |  | ) | `[inline, inherited]`

Locale access.

Returns:
  The current locale in effect.

If pubimbue(loc) has been called, then the most recent `loc` is returned. Otherwise the global locale in effect at the time of construction is returned.

Definition at line 268 of file streambuf.

Referenced by std::basic_istream< _CharT, _Traits >::sync().

template<typename _CharT, typename _Traits>

int_type std::basic_streambuf< _CharT, _Traits >::sbumpc | ( |  | ) | `[inline, inherited]`

Getting the next character.

Returns:
  The next character, or eof.

If the input read position is available, returns that character and increments the read pointer, otherwise calls and returns `uflow()`.

Definition at line 313 of file streambuf.

Referenced by std::basic_istream< _CharT, _Traits >::getline(), std::basic_istream< _CharT, _Traits >::ignore(), std::istreambuf_iterator< _CharT, _Traits >::operator++(), and std::operator>>().

template<typename _CharT, typename _Traits>

basic_filebuf< _CharT, _Traits >::pos_type std::basic_filebuf< _CharT, _Traits >::seekoff | ( | off_type | __off,
|  | ios_base::seekdir | __way,
|  | ios_base::openmode | __mode = `ios_base::in | ios_base::out` |
| ) |  |  | `[protected, virtual]`

Alters the stream positions.

Each derived class provides its own appropriate behavior.

Note:
  Base class version does nothing, returns a `pos_type` that represents an invalid stream position.

Reimplemented from std::basic_streambuf< _CharT, _Traits >.

Definition at line 668 of file fstream.tcc.

References std::basic_filebuf< _CharT, _Traits >::_M_codecvt, std::basic_filebuf< _CharT, _Traits >::_M_destroy_pback(), std::basic_filebuf< _CharT, _Traits >::_M_ext_buf, std::basic_filebuf< _CharT, _Traits >::_M_ext_end, std::basic_filebuf< _CharT, _Traits >::_M_ext_next, std::basic_filebuf< _CharT, _Traits >::_M_reading, std::basic_filebuf< _CharT, _Traits >::_M_seek(), std::basic_filebuf< _CharT, _Traits >::_M_state_beg, std::basic_filebuf< _CharT, _Traits >::_M_state_last, std::__codecvt_abstract_base< _InternT, _ExternT, _StateT >::always_noconv(), std::ios_base::cur, std::basic_streambuf< _CharT, _Traits >::eback(), std::basic_streambuf< _CharT, _Traits >::egptr(), std::__codecvt_abstract_base< _InternT, _ExternT, _StateT >::encoding(), and std::__codecvt_abstract_base< _InternT, _ExternT, _StateT >::length().

Referenced by std::basic_filebuf< _CharT, _Traits >::imbue().

template<typename _CharT, typename _Traits>

basic_filebuf< _CharT, _Traits >::pos_type std::basic_filebuf< _CharT, _Traits >::seekpos | ( | pos_type | __pos,
|  | ios_base::openmode | __mode = `ios_base::in | ios_base::out` |
| ) |  |  | `[protected, virtual]`

Alters the stream positions.

Each derived class provides its own appropriate behavior.

Note:
  Base class version does nothing, returns a `pos_type` that represents an invalid stream position.

Reimplemented from std::basic_streambuf< _CharT, _Traits >.

Definition at line 721 of file fstream.tcc.

References std::basic_filebuf< _CharT, _Traits >::_M_destroy_pback(), std::basic_filebuf< _CharT, _Traits >::_M_seek(), and std::ios_base::beg.

template<typename _CharT, typename _Traits>

basic_filebuf< _CharT, _Traits >::__streambuf_type * std::basic_filebuf< _CharT, _Traits >::setbuf | ( | char_type * | __s,
|  | streamsize | __n |
| ) |  |  | `[protected, virtual]`

Manipulates the buffer.

Parameters:

  | s | Pointer to a buffer area.
  | n | Size of s.

Returns:
  `this`

If no file has been opened, and both s and n are zero, then the stream becomes unbuffered. Otherwise, `s` is used as a buffer; see http://gcc.gnu.org/onlinedocs/libstdc++/27_io/howto.html#2 for more.

Reimplemented from std::basic_streambuf< _CharT, _Traits >.

Definition at line 641 of file fstream.tcc.

References std::basic_filebuf< _CharT, _Traits >::_M_buf, and std::basic_filebuf< _CharT, _Traits >::_M_buf_size.

template<typename _CharT, typename _Traits>

void std::basic_streambuf< _CharT, _Traits >::setg | ( | char_type * | __gbeg,
|  | char_type * | __gnext,
|  | char_type * | __gend |
| ) |  |  | `[inline, protected, inherited]`

Setting the three read area pointers.

Parameters:

  | gbeg | A pointer.
  | gnext | A pointer.
  | gend | A pointer.

Postcondition:
  gbeg == `eback()`, gnext == `gptr()`, and gend == `egptr()`

Definition at line 505 of file streambuf.

Referenced by std::basic_stringbuf< _CharT, _Traits, _Alloc >::_M_sync().

template<typename _CharT, typename _Traits>

void std::basic_streambuf< _CharT, _Traits >::setp | ( | char_type * | __pbeg,
|  | char_type * | __pend |
| ) |  |  | `[inline, protected, inherited]`

Setting the three write area pointers.

Parameters:

  | pbeg | A pointer.
  | pend | A pointer.

Postcondition:
  pbeg == `pbase()`, pbeg == `pptr()`, and pend == `epptr()`

Definition at line 551 of file streambuf.

Referenced by std::basic_stringbuf< _CharT, _Traits, _Alloc >::_M_sync().

template<typename _CharT, typename _Traits>

int_type std::basic_streambuf< _CharT, _Traits >::sgetc | ( |  | ) | `[inline, inherited]`

Getting the next character.

Returns:
  The next character, or eof.

If the input read position is available, returns that character, otherwise calls and returns `underflow()`. Does not move the read position after fetching the character.

Definition at line 335 of file streambuf.

Referenced by std::__copy_streambufs_eof(), std::basic_istream< _CharT, _Traits >::get(), std::basic_istream< _CharT, _Traits >::getline(), std::basic_istream< _CharT, _Traits >::ignore(), and std::basic_istream< _CharT, _Traits >::sentry::sentry().

template<typename _CharT, typename _Traits>

streamsize std::basic_streambuf< _CharT, _Traits >::sgetn | ( | char_type * | __s,
|  | streamsize | __n |
| ) |  |  | `[inline, inherited]`

Entry point for xsgetn.

Parameters:

  | s | A buffer area.
  | n | A count.

Returns xsgetn(s,n). The effect is to fill s[0] through s[n-1] with characters from the input sequence, if possible.

Definition at line 354 of file streambuf.

template<typename _CharT, typename _Traits>

streamsize std::basic_filebuf< _CharT, _Traits >::showmanyc | ( |  | ) | `[protected, virtual]`

Investigating the data available.

Returns:
  An estimate of the number of characters available in the input sequence, or -1.

"If it returns a positive value, then successive calls to `underflow()` will not return `traits::eof()` until at least that number of characters have been supplied. If `showmanyc()` returns -1, then calls to `underflow()` or `uflow()` will fail." [27.5.2.4.3]/1

Note:
  Base class version does nothing, returns zero.

  The standard adds that "the intention is not only that the calls [to underflow or uflow] will not return `eof()` but that they will return "immediately".

  The standard adds that "the morphemes of `showmanyc` are "es-how-many-see", not "show-manic".

Reimplemented from std::basic_streambuf< _CharT, _Traits >.

Definition at line 165 of file fstream.tcc.

References std::__check_facet(), std::basic_filebuf< _CharT, _Traits >::_M_codecvt, std::basic_filebuf< _CharT, _Traits >::_M_file, std::basic_filebuf< _CharT, _Traits >::_M_mode, std::ios_base::binary, std::basic_streambuf< _CharT, _Traits >::gptr(), std::ios_base::in, and std::__basic_file< char >::showmanyc().

template<typename _CharT, typename _Traits>

int_type std::basic_streambuf< _CharT, _Traits >::snextc | ( |  | ) | `[inline, inherited]`

Getting the next character.

Returns:
  The next character, or eof.

Calls `sbumpc()`, and if that function returns `traits::eof()`, so does this function. Otherwise, `sgetc()`.

Definition at line 295 of file streambuf.

Referenced by std::__copy_streambufs_eof(), std::basic_istream< _CharT, _Traits >::get(), std::basic_istream< _CharT, _Traits >::getline(), std::basic_istream< _CharT, _Traits >::ignore(), and std::basic_istream< _CharT, _Traits >::sentry::sentry().

template<typename _CharT, typename _Traits>

int_type std::basic_streambuf< _CharT, _Traits >::sputbackc | ( | char_type | __c | ) | `[inline, inherited]`

Pushing characters back into the input stream.

Parameters:

  | c | The character to push back.

Returns:
  The previous character, if possible.

Similar to sungetc(), but c is pushed onto the stream instead of "the previous character". If successful, the next character fetched from the input stream will be c.

Definition at line 368 of file streambuf.

Referenced by std::operator>>(), and std::basic_istream< _CharT, _Traits >::putback().

template<typename _CharT, typename _Traits>

int_type std::basic_streambuf< _CharT, _Traits >::sputc | ( | char_type | __c | ) | `[inline, inherited]`

Entry point for all single-character output functions.

Parameters:

  | c | A character to output.

Returns:
  c, if possible.

One of two public output functions.

If a write position is available for the output sequence (i.e., the buffer is not full), stores c in that position, increments the position, and returns `traits::to_int_type(c)`. If a write position is not available, returns `overflow(c)`.

Definition at line 420 of file streambuf.

Referenced by std::__copy_streambufs_eof(), std::basic_istream< _CharT, _Traits >::get(), and std::ostreambuf_iterator< _CharT, _Traits >::operator=().

template<typename _CharT, typename _Traits>

streamsize std::basic_streambuf< _CharT, _Traits >::sputn | ( | const char_type * | __s,
|  | streamsize | __n |
| ) |  |  | `[inline, inherited]`

Entry point for all single-character output functions.

Parameters:

  | s | A buffer read area.
  | n | A count.

One of two public output functions.

Returns xsputn(s,n). The effect is to write s[0] through s[n-1] to the output sequence, if possible.

Definition at line 446 of file streambuf.

template<typename _CharT, typename _Traits>

void std::basic_streambuf< _CharT, _Traits >::stossc | ( |  | ) | `[inline, inherited]`

Tosses a character.

Advances the read pointer, ignoring the character that would have been read.

See http://gcc.gnu.org/ml/libstdc++/2002-05/msg00168.html

Note:
  This function has been deprecated by the standard. You must define `_GLIBCXX_DEPRECATED` to make this visible; see c++config.h.

Definition at line 782 of file streambuf.

template<typename _CharT, typename _Traits>

int_type std::basic_streambuf< _CharT, _Traits >::sungetc | ( |  | ) | `[inline, inherited]`

Moving backwards in the input stream.

Returns:
  The previous character, if possible.

If a putback position is available, this function decrements the input pointer and returns that character. Otherwise, calls and returns pbackfail(). The effect is to "unget" the last character "gotten".

Definition at line 393 of file streambuf.

Referenced by std::basic_istream< _CharT, _Traits >::unget().

template<typename _CharT, typename _Traits>

int std::basic_filebuf< _CharT, _Traits >::sync | ( |  | ) | `[protected, virtual]`

Synchronizes the buffer arrays with the controlled sequences.

Returns:
  -1 on failure.

Each derived class provides its own appropriate behavior, including the definition of "failure".

Note:
  Base class version does nothing, returns zero.

Reimplemented from std::basic_streambuf< _CharT, _Traits >.

Definition at line 820 of file fstream.tcc.

References std::basic_streambuf< _CharT, _Traits >::pptr().

template<typename _CharT, typename _Traits>

virtual int_type std::basic_streambuf< _CharT, _Traits >::uflow | ( |  | ) | `[inline, protected, virtual, inherited]`

Fetches more data from the controlled sequence.

Returns:
  The first character from the pending sequence.

Informally, this function does the same thing as `underflow()`, and in fact is required to call that function. It also returns the new character, like `underflow()` does. However, this function also moves the read position forward by one.

Reimplemented in __gnu_cxx::stdio_sync_filebuf< _CharT, _Traits >.

Definition at line 696 of file streambuf.

template<typename _CharT, typename _Traits>

basic_filebuf< _CharT, _Traits >::int_type std::basic_filebuf< _CharT, _Traits >::underflow | ( |  | ) | `[protected, virtual]`

Fetches more data from the controlled sequence.

Returns:
  The first character from the pending sequence.

Informally, this function is called when the input buffer is exhausted (or does not exist, as buffering need not actually be done). If a buffer exists, it is "refilled". In either case, the next available character is returned, or `traits::eof()` to indicate a null pending sequence.

For a formal definiton of the pending sequence, see a good text such as Langer & Kreft, or [27.5.2.4.3]/7-14.

A functioning input streambuf can be created by overriding only this function (no buffer area will be used). For an example, see http://gcc.gnu.org/onlinedocs/libstdc++/27_io/howto.html#6

Note:
  Base class version does nothing, returns eof().

Reimplemented from std::basic_streambuf< _CharT, _Traits >.

Definition at line 191 of file fstream.tcc.

References std::__check_facet(), __N, std::basic_filebuf< _CharT, _Traits >::_M_buf_size, std::basic_filebuf< _CharT, _Traits >::_M_codecvt, std::basic_filebuf< _CharT, _Traits >::_M_destroy_pback(), std::basic_filebuf< _CharT, _Traits >::_M_ext_buf, std::basic_filebuf< _CharT, _Traits >::_M_ext_buf_size, std::basic_filebuf< _CharT, _Traits >::_M_ext_end, std::basic_filebuf< _CharT, _Traits >::_M_ext_next, std::basic_filebuf< _CharT, _Traits >::_M_file, std::basic_filebuf< _CharT, _Traits >::_M_mode, std::basic_filebuf< _CharT, _Traits >::_M_reading, std::basic_filebuf< _CharT, _Traits >::_M_set_buffer(), std::basic_filebuf< _CharT, _Traits >::_M_state_cur, std::basic_filebuf< _CharT, _Traits >::_M_state_last, std::basic_filebuf< _CharT, _Traits >::_M_writing, std::copy(), std::basic_streambuf< _CharT, _Traits >::eback(), std::basic_streambuf< _CharT, _Traits >::egptr(), std::__codecvt_abstract_base< _InternT, _ExternT, _StateT >::encoding(), std::__codecvt_abstract_base< _InternT, _ExternT, _StateT >::in(), std::ios_base::in, std::__codecvt_abstract_base< _InternT, _ExternT, _StateT >::max_length(), std::min(), and std::__basic_file< char >::xsgetn().

template<typename _CharT, typename _Traits>

streamsize std::basic_filebuf< _CharT, _Traits >::xsgetn | ( | char_type * | __s,
|  | streamsize | __n |
| ) |  |  | `[protected, virtual]`

Multiple character extraction.

Parameters:

  | s | A buffer area.
  | n | Maximum number of characters to assign.

Returns:
  The number of characters assigned.

Fills s[0] through s[n-1] with characters from the input sequence, as if by `sbumpc()`. Stops when either n characters have been copied, or when `traits::eof()` would be copied.

It is expected that derived classes provide a more efficient implementation by overriding this definition.

Reimplemented from std::basic_streambuf< _CharT, _Traits >.

Definition at line 511 of file fstream.tcc.

References std::__check_facet(), __N, std::basic_filebuf< _CharT, _Traits >::_M_buf_size, std::basic_filebuf< _CharT, _Traits >::_M_codecvt, std::basic_filebuf< _CharT, _Traits >::_M_destroy_pback(), std::basic_filebuf< _CharT, _Traits >::_M_file, std::basic_filebuf< _CharT, _Traits >::_M_mode, std::basic_filebuf< _CharT, _Traits >::_M_pback_init, std::basic_filebuf< _CharT, _Traits >::_M_reading, std::basic_filebuf< _CharT, _Traits >::_M_set_buffer(), std::basic_filebuf< _CharT, _Traits >::_M_writing, std::copy(), std::basic_streambuf< _CharT, _Traits >::eback(), std::basic_streambuf< _CharT, _Traits >::egptr(), std::basic_streambuf< _CharT, _Traits >::gbump(), std::basic_streambuf< _CharT, _Traits >::gptr(), std::ios_base::in, std::basic_streambuf< _CharT, _Traits >::xsgetn(), and std::__basic_file< char >::xsgetn().

template<typename _CharT, typename _Traits>

streamsize std::basic_filebuf< _CharT, _Traits >::xsputn | ( | const char_type * | __s,
|  | streamsize | __n |
| ) |  |  | `[protected, virtual]`

Multiple character insertion.

Parameters:

  | s | A buffer area.
  | n | Maximum number of characters to write.

Returns:
  The number of characters written.

Writes s[0] through s[n-1] to the output sequence, as if by `sputc()`. Stops when either n characters have been copied, or when `sputc()` would return `traits::eof()`.

It is expected that derived classes provide a more efficient implementation by overriding this definition.

Reimplemented from std::basic_streambuf< _CharT, _Traits >.

Definition at line 594 of file fstream.tcc.

References std::__check_facet(), std::basic_filebuf< _CharT, _Traits >::_M_buf_size, std::basic_filebuf< _CharT, _Traits >::_M_codecvt, std::basic_filebuf< _CharT, _Traits >::_M_file, std::basic_filebuf< _CharT, _Traits >::_M_mode, std::basic_filebuf< _CharT, _Traits >::_M_reading, std::basic_filebuf< _CharT, _Traits >::_M_set_buffer(), std::basic_filebuf< _CharT, _Traits >::_M_writing, std::basic_streambuf< _CharT, _Traits >::epptr(), std::min(), std::ios_base::out, std::basic_streambuf< _CharT, _Traits >::pbase(), std::basic_streambuf< _CharT, _Traits >::pptr(), std::basic_streambuf< _CharT, _Traits >::xsputn(), and std::__basic_file< char >::xsputn_2().

## Member Data Documentation

template<typename _CharT, typename _Traits>

locale std::basic_streambuf< _CharT, _Traits >::_M_buf_locale `[protected, inherited]`

Locale access.

Returns:
  The current locale in effect.

If pubimbue(loc) has been called, then the most recent `loc` is returned. Otherwise the global locale in effect at the time of construction is returned.

Definition at line 207 of file streambuf.

Referenced by std::basic_filebuf< _CharT, _Traits >::basic_filebuf().

template<typename _CharT, typename _Traits>

char_type* std::basic_streambuf< _CharT, _Traits >::_M_in_beg `[protected, inherited]`

Locale access.

Returns:
  The current locale in effect.

If pubimbue(loc) has been called, then the most recent `loc` is returned. Otherwise the global locale in effect at the time of construction is returned.

Definition at line 195 of file streambuf.

template<typename _CharT, typename _Traits>

char_type* std::basic_streambuf< _CharT, _Traits >::_M_in_cur `[protected, inherited]`

Locale access.

Returns:
  The current locale in effect.

If pubimbue(loc) has been called, then the most recent `loc` is returned. Otherwise the global locale in effect at the time of construction is returned.

Definition at line 196 of file streambuf.

template<typename _CharT, typename _Traits>

char_type* std::basic_streambuf< _CharT, _Traits >::_M_in_end `[protected, inherited]`

Locale access.

Returns:
  The current locale in effect.

If pubimbue(loc) has been called, then the most recent `loc` is returned. Otherwise the global locale in effect at the time of construction is returned.

Definition at line 197 of file streambuf.

template<typename _CharT, typename _Traits>

char_type* std::basic_streambuf< _CharT, _Traits >::_M_out_beg `[protected, inherited]`

Locale access.

Returns:
  The current locale in effect.

If pubimbue(loc) has been called, then the most recent `loc` is returned. Otherwise the global locale in effect at the time of construction is returned.

Definition at line 198 of file streambuf.

template<typename _CharT, typename _Traits>

char_type* std::basic_streambuf< _CharT, _Traits >::_M_out_cur `[protected, inherited]`

Locale access.

Returns:
  The current locale in effect.

If pubimbue(loc) has been called, then the most recent `loc` is returned. Otherwise the global locale in effect at the time of construction is returned.

Definition at line 199 of file streambuf.

template<typename _CharT, typename _Traits>

char_type* std::basic_streambuf< _CharT, _Traits >::_M_out_end `[protected, inherited]`

Locale access.

Returns:
  The current locale in effect.

If pubimbue(loc) has been called, then the most recent `loc` is returned. Otherwise the global locale in effect at the time of construction is returned.

Definition at line 200 of file streambuf.

The documentation for this class was generated from the following files:

- fstream
- fstream.tcc