Public Types

typedef _CharT char_type
typedef _Traits traits_type
typedef traits_type::int_type int_type
typedef traits_type::pos_type pos_type
typedef traits_type::off_type off_type

typedef basic_streambuf< char_type, traits_type > __streambuf_type
This is a non-standard type.

Public Member Functions

virtual ~basic_streambuf ()
Destructor deallocates no buffer space. locale getloc () const
Locale access. streamsize in_avail ()
Looking ahead into the stream. locale pubimbue (const locale &__loc)
Entry point for imbue(). int_type sbumpc ()
Getting the next character. int_type sgetc ()
Getting the next character. streamsize sgetn (char_type *__s, streamsize __n)
Entry point for xsgetn. int_type snextc ()
Getting the next character. int_type sputbackc (char_type __c)
Pushing characters back into the input stream. int_type sputc (char_type __c)
Entry point for all single-character output functions. streamsize sputn (const char_type *__s, streamsize __n)
Entry point for all single-character output functions. int_type sungetc ()
Moving backwards in the input stream.

basic_streambuf * pubsetbuf (char_type *__s, streamsize __n)
Entry points for derived buffer functions. pos_type pubseekoff (off_type __off, ios_base::seekdir __way, ios_base::openmode __mode=ios_base::in|ios_base::out)
Alters the stream position. pos_type pubseekpos (pos_type __sp, ios_base::openmode __mode=ios_base::in|ios_base::out)
Alters the stream position. int pubsync ()
Calls virtual sync function.

Protected Member Functions

basic_streambuf ()
Base constructor. basic_streambuf (const basic_streambuf &)
void __safe_gbump (streamsize __n)
void __safe_pbump (streamsize __n)
void gbump (int __n)
Moving the read position. virtual void imbue (const locale &__loc)
Changes translations. basic_streambuf & operator= (const basic_streambuf &)
virtual int_type overflow (int_type __c=traits_type::eof())
Consumes data from the buffer; writes to the controlled sequence. virtual int_type pbackfail (int_type __c=traits_type::eof())
Tries to back up the input sequence. void pbump (int __n)
Moving the write position. virtual pos_type seekoff (off_type, ios_base::seekdir, ios_base::openmode=ios_base::in|ios_base::out)
Alters the stream positions. virtual pos_type seekpos (pos_type, ios_base::openmode=ios_base::in|ios_base::out)
Alters the stream positions. virtual basic_streambuf< char_type, _Traits > * setbuf (char_type *, streamsize)
Manipulates the buffer. void setg (char_type *__gbeg, char_type *__gnext, char_type *__gend)
Setting the three read area pointers. void setp (char_type *__pbeg, char_type *__pend)
Setting the three write area pointers. virtual streamsize showmanyc ()
Investigating the data available. void swap (basic_streambuf &__sb)
virtual int sync ()
Synchronizes the buffer arrays with the controlled sequences. virtual int_type uflow ()
Fetches more data from the controlled sequence. virtual int_type underflow ()
Fetches more data from the controlled sequence. virtual streamsize xsgetn (char_type *__s, streamsize __n)
Multiple character extraction. virtual streamsize xsputn (const char_type *__s, streamsize __n)
Multiple character insertion.

char_type * eback () const
Access to the get area. char_type * gptr () const
Access to the get area. char_type * egptr () const
Access to the get area.

char_type * pbase () const
Access to the put area. char_type * pptr () const
Access to the put area. char_type * epptr () const
Access to the put area.

Protected Attributes

locale _M_buf_locale
Current locale setting. char_type * _M_in_beg
Start of get area. char_type * _M_in_cur
Current read area. char_type * _M_in_end
End of get area. char_type * _M_out_beg
Start of put area. char_type * _M_out_cur
Current put area. char_type * _M_out_end
End of put area.

Friends

template<bool _IsMove, typename _CharT2 > __gnu_cxx::__enable_if< __is_char< _CharT2 >::__value, _CharT2 * >::__type __copy_move_a2 (istreambuf_iterator< _CharT2 >, istreambuf_iterator< _CharT2 >, _CharT2 *)
streamsize __copy_streambufs_eof (basic_streambuf *, basic_streambuf *, bool &)
void __istream_extract (istream &, char *, streamsize)
template<typename _CharT2 , typename _Distance > __gnu_cxx::__enable_if< __is_char< _CharT2 >::__value, void >::__type advance (istreambuf_iterator< _CharT2 > &, _Distance)
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 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 > &)
class ostreambuf_iterator< char_type, traits_type >

template<typename _CharT, typename _Traits>

class std::basic_streambuf< _CharT, _Traits >"The actual work of input and output (interface).

Template Parameters

This is a base class. Derived stream buffers each control a pair of character sequences: one for input, and one for output.

Section [27.5.1] of the standard describes the requirements and behavior of stream buffer classes. That section (three paragraphs) is reproduced here, for simplicity and accuracy.

1.

Stream buffers can impose various constraints on the sequences they control. Some constraints are:

•

The controlled input sequence can be not readable.

•

The controlled output sequence can be not writable.

•

The controlled sequences can be associated with the contents of other representations for character sequences, such as external files.

•

The controlled sequences can support operations directly to or from associated sequences.

•

The controlled sequences can impose limitations on how the program can read characters from a sequence, write characters to a sequence, put characters back into an input sequence, or alter the stream position.

2.

Each sequence is characterized by three pointers which, if non-null, all point into the same charT array object. The array object represents, at any moment, a (sub)sequence of characters from the sequence. Operations performed on a sequence alter the values stored in these pointers, perform reads and writes directly to or from associated sequences, and alter the stream position and conversion state as needed to maintain this subsequence relationship. The three pointers are:

•

the beginning pointer, or lowest element address in the array (called xbeg here);

•

the next pointer, or next element address that is a current candidate for reading or writing (called xnext here);

•

the end pointer, or first element address beyond the end of the array (called xend here).

3.

The following semantic constraints shall always apply for any set of three pointers for a sequence, using the pointer names given immediately above:

•

If xnext is not a null pointer, then xbeg and xend shall also be non-null pointers into the same charT array, as described above; otherwise, xbeg and xend shall also be null.

•

If xnext is not a null pointer and xnext < xend for an output sequence, then a write position is available. In this case, *xnext shall be assignable as the next element to write (to put, or to store a character value, into the sequence).

•

If xnext is not a null pointer and xbeg < xnext for an input sequence, then a putback position is available. In this case, xnext[-1] shall have a defined value and is the next (preceding) element to store a character that is put back into the input sequence.

•

If xnext is not a null pointer and xnext< xend for an input sequence, then a read position is available. In this case, *xnext shall have a defined value and is the next element to read (to get, or to obtain a character value, from the sequence).

Definition at line 122 of file streambuf.

template<typename _CharT , typename _Traits > typedef basic_streambuf<char_type, traits_type> std::basic_streambuf< _CharT, _Traits >::__streambuf_type

This is a non-standard type.

Definition at line 140 of file streambuf.

template<typename _CharT , typename _Traits > typedef _CharT std::basic_streambuf< _CharT, _Traits >::char_type

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

Definition at line 131 of file streambuf.

template<typename _CharT , typename _Traits > typedef traits_type::int_type std::basic_streambuf< _CharT, _Traits >::int_type

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

Definition at line 133 of file streambuf.

template<typename _CharT , typename _Traits > typedef traits_type::off_type std::basic_streambuf< _CharT, _Traits >::off_type

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

Definition at line 135 of file streambuf.

template<typename _CharT , typename _Traits > typedef traits_type::pos_type std::basic_streambuf< _CharT, _Traits >::pos_type

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

Definition at line 134 of file streambuf.

template<typename _CharT , typename _Traits > typedef _Traits std::basic_streambuf< _CharT, _Traits >::traits_type

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

Definition at line 132 of file streambuf.

template<typename _CharT , typename _Traits > virtual std::basic_streambuf< _CharT, _Traits >::~basic_streambuf () [inline], [virtual]

Destructor deallocates no buffer space.

Definition at line 202 of file streambuf.

template<typename _CharT , typename _Traits > std::basic_streambuf< _CharT, _Traits >::basic_streambuf () [inline], [protected]

Base constructor. Only called from derived constructors, and sets up all the buffer data to zero, including the pointers described in the basic_streambuf class description. Note that, as a result,

• the class starts with no read nor write positions available,
• this is not an error

Definition at line 468 of file streambuf.

template<typename _CharT , typename _Traits > void std::basic_streambuf< _CharT, _Traits >::__safe_gbump (streamsize __n) [inline], [protected]

Definition at line 800 of file streambuf.

template<typename _CharT , typename _Traits > void std::basic_streambuf< _CharT, _Traits >::__safe_pbump (streamsize __n) [inline], [protected]

Definition at line 803 of file streambuf.

template<typename _CharT , typename _Traits > char_type * std::basic_streambuf< _CharT, _Traits >::eback () const [inline], [protected]

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 487 of file streambuf.

template<typename _CharT , typename _Traits > char_type * std::basic_streambuf< _CharT, _Traits >::egptr () const [inline], [protected]

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 493 of file streambuf.

template<typename _CharT , typename _Traits > char_type * std::basic_streambuf< _CharT, _Traits >::epptr () const [inline], [protected]

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 540 of file streambuf.

template<typename _CharT , typename _Traits > void std::basic_streambuf< _CharT, _Traits >::gbump (int __n) [inline], [protected]

Moving the read position.

Parameters

This just advances the read position without returning any data.

Definition at line 503 of file streambuf.

template<typename _CharT , typename _Traits > locale std::basic_streambuf< _CharT, _Traits >::getloc () const [inline]

Locale access.

Returns

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 231 of file streambuf.

template<typename _CharT , typename _Traits > char_type * std::basic_streambuf< _CharT, _Traits >::gptr () const [inline], [protected]

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 490 of file streambuf.

template<typename _CharT , typename _Traits > virtual void std::basic_streambuf< _CharT, _Traits >::imbue (const locale & __loc) [inline], [protected], [virtual]

Changes translations.

Parameters

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

Reimplemented in std::basic_filebuf< _CharT, _Traits >, std::basic_filebuf< _CharT, encoding_char_traits< _CharT > >, std::basic_filebuf< _CharT, std::char_traits< _CharT > >, and std::basic_filebuf< char_type, traits_type >.

Definition at line 581 of file streambuf.

template<typename _CharT , typename _Traits > streamsize std::basic_streambuf< _CharT, _Traits >::in_avail () [inline]

Looking ahead into the stream.

Returns

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 289 of file streambuf.

template<typename _CharT , typename _Traits > virtual int_type std::basic_streambuf< _CharT, _Traits >::overflow (int_type __c = traits_type::eof()) [inline], [protected], [virtual]

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

Parameters

Returns

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 definition 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

Reimplemented in std::basic_filebuf< _CharT, _Traits >, std::basic_filebuf< _CharT, encoding_char_traits< _CharT > >, std::basic_filebuf< char_type, traits_type >, std::basic_stringbuf< _CharT, _Traits, _Alloc >, and std::wbuffer_convert< _Codecvt, _Elem, _Tr >.

Definition at line 773 of file streambuf.

template<typename _CharT , typename _Traits > virtual int_type std::basic_streambuf< _CharT, _Traits >::pbackfail (int_type __c = traits_type::eof()) [inline], [protected], [virtual]

Tries to back up the input sequence.

Parameters

Returns

Postcondition

Note

Reimplemented in std::basic_filebuf< _CharT, _Traits >, std::basic_filebuf< _CharT, encoding_char_traits< _CharT > >, std::basic_filebuf< char_type, traits_type >, and std::basic_stringbuf< _CharT, _Traits, _Alloc >.

Definition at line 729 of file streambuf.

template<typename _CharT , typename _Traits > char_type * std::basic_streambuf< _CharT, _Traits >::pbase () const [inline], [protected]

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 534 of file streambuf.

template<typename _CharT , typename _Traits > void std::basic_streambuf< _CharT, _Traits >::pbump (int __n) [inline], [protected]

Moving the write position.

Parameters

This just advances the write position without returning any data.

Definition at line 550 of file streambuf.

template<typename _CharT , typename _Traits > char_type * std::basic_streambuf< _CharT, _Traits >::pptr () const [inline], [protected]

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 537 of file streambuf.

template<typename _CharT , typename _Traits > locale std::basic_streambuf< _CharT, _Traits >::pubimbue (const locale & __loc) [inline]

Entry point for imbue().

Parameters

Returns

Calls the derived imbue(__loc).

Definition at line 214 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]

Alters the stream position.

Parameters

Calls virtual seekoff function.

Definition at line 256 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]

Alters the stream position.

Parameters

Calls virtual seekpos function.

Definition at line 268 of file streambuf.

template<typename _CharT , typename _Traits > basic_streambuf * std::basic_streambuf< _CharT, _Traits >::pubsetbuf (char_type * __s, streamsize __n) [inline]

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 244 of file streambuf.

template<typename _CharT , typename _Traits > int std::basic_streambuf< _CharT, _Traits >::pubsync () [inline]

Calls virtual sync function.

Definition at line 276 of file streambuf.

Referenced by std::wbuffer_convert< _Codecvt, _Elem, _Tr >::sync().

template<typename _CharT , typename _Traits > int_type std::basic_streambuf< _CharT, _Traits >::sbumpc () [inline]

Getting the next character.

Returns

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

Definition at line 321 of file streambuf.

template<typename _CharT , typename _Traits > virtual pos_type std::basic_streambuf< _CharT, _Traits >::seekoff (off_type, ios_base::seekdir, ios_base::openmode = ios_base::in | ios_base::out) [inline], [protected], [virtual]

Alters the stream positions. Each derived class provides its own appropriate behavior.

Note

Reimplemented in std::basic_filebuf< _CharT, _Traits >, std::basic_filebuf< _CharT, encoding_char_traits< _CharT > >, std::basic_filebuf< char_type, traits_type >, and std::basic_stringbuf< _CharT, _Traits, _Alloc >.

Definition at line 607 of file streambuf.

template<typename _CharT , typename _Traits > virtual pos_type std::basic_streambuf< _CharT, _Traits >::seekpos (pos_type, ios_base::openmode = ios_base::in | ios_base::out) [inline], [protected], [virtual]

Alters the stream positions. Each derived class provides its own appropriate behavior.

Note

Reimplemented in std::basic_filebuf< _CharT, _Traits >, std::basic_filebuf< _CharT, encoding_char_traits< _CharT > >, std::basic_filebuf< char_type, traits_type >, std::basic_stringbuf< _CharT, _Traits, _Alloc >, and __gnu_cxx::stdio_sync_filebuf< _CharT, _Traits >.

Definition at line 619 of file streambuf.

template<typename _CharT , typename _Traits > virtual basic_streambuf< char_type, _Traits > * std::basic_streambuf< _CharT, _Traits >::setbuf (char_type *, streamsize) [inline], [protected], [virtual]

Manipulates the buffer. Each derived class provides its own appropriate behavior. See the next-to-last paragraph of https://gcc.gnu.org/onlinedocs/libstdc++/manual/streambufs.html#io.streambuf.buffering for more on this function.

Note

Reimplemented in std::basic_filebuf< _CharT, _Traits >, std::basic_filebuf< _CharT, encoding_char_traits< _CharT > >, std::basic_filebuf< _CharT, std::char_traits< _CharT > >, std::basic_filebuf< char_type, traits_type >, and std::basic_stringbuf< _CharT, _Traits, _Alloc >.

Definition at line 596 of file streambuf.

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

Setting the three read area pointers.

Parameters

Postcondition

Definition at line 514 of file streambuf.

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

Setting the three write area pointers.

Parameters

Postcondition

Definition at line 560 of file streambuf.

template<typename _CharT , typename _Traits > int_type std::basic_streambuf< _CharT, _Traits >::sgetc () [inline]

Getting the next character.

Returns

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 343 of file streambuf.

Referenced by std::basic_istream< char >::seekg().

template<typename _CharT , typename _Traits > streamsize std::basic_streambuf< _CharT, _Traits >::sgetn (char_type * __s, streamsize __n) [inline]

Entry point for xsgetn.

Parameters

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 362 of file streambuf.

template<typename _CharT , typename _Traits > virtual streamsize std::basic_streambuf< _CharT, _Traits >::showmanyc () [inline], [protected], [virtual]

Investigating the data available.

Returns

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

Reimplemented in std::basic_filebuf< _CharT, _Traits >, std::basic_filebuf< _CharT, encoding_char_traits< _CharT > >, std::basic_filebuf< _CharT, std::char_traits< _CharT > >, std::basic_filebuf< char_type, traits_type >, and std::basic_stringbuf< _CharT, _Traits, _Alloc >.

Definition at line 654 of file streambuf.

template<typename _CharT , typename _Traits > int_type std::basic_streambuf< _CharT, _Traits >::snextc () [inline]

Getting the next character.

Returns

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

Definition at line 303 of file streambuf.

Referenced by std::basic_istream< char >::putback(), and std::basic_istream< char >::seekg().

template<typename _CharT , typename _Traits > int_type std::basic_streambuf< _CharT, _Traits >::sputbackc (char_type __c) [inline]

Pushing characters back into the input stream.

Parameters

Returns

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 377 of file streambuf.

template<typename _CharT , typename _Traits > int_type std::basic_streambuf< _CharT, _Traits >::sputc (char_type __c) [inline]

Entry point for all single-character output functions.

Parameters

Returns

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 429 of file streambuf.

Referenced by 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]

Entry point for all single-character output functions.

Parameters

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 455 of file streambuf.

template<typename _CharT , typename _Traits > int_type std::basic_streambuf< _CharT, _Traits >::sungetc () [inline]

Moving backwards in the input stream.

Returns

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 402 of file streambuf.

template<typename _CharT , typename _Traits > void std::basic_streambuf< _CharT, _Traits >::swap (basic_streambuf< _CharT, _Traits > & __sb) [inline], [protected]

Definition at line 817 of file streambuf.

template<typename _CharT , typename _Traits > virtual int std::basic_streambuf< _CharT, _Traits >::sync (void) [inline], [protected], [virtual]

Synchronizes the buffer arrays with the controlled sequences.

Returns

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

Note

Reimplemented in std::wbuffer_convert< _Codecvt, _Elem, _Tr >, __gnu_cxx::stdio_sync_filebuf< _CharT, _Traits >, std::basic_filebuf< _CharT, _Traits >, std::basic_filebuf< _CharT, encoding_char_traits< _CharT > >, std::basic_filebuf< _CharT, std::char_traits< _CharT > >, and std::basic_filebuf< char_type, traits_type >.

Definition at line 632 of file streambuf.

template<typename _CharT , typename _Traits > virtual int_type std::basic_streambuf< _CharT, _Traits >::uflow () [inline], [protected], [virtual]

Fetches more data from the controlled sequence.

Returns

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 705 of file streambuf.

template<typename _CharT , typename _Traits > virtual int_type std::basic_streambuf< _CharT, _Traits >::underflow () [inline], [protected], [virtual]

Fetches more data from the controlled sequence.

Returns

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 definition 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 https://gcc.gnu.org/onlinedocs/libstdc++/manual/streambufs.html

Note

Reimplemented in std::wbuffer_convert< _Codecvt, _Elem, _Tr >, __gnu_cxx::stdio_sync_filebuf< _CharT, _Traits >, std::basic_filebuf< _CharT, _Traits >, std::basic_filebuf< _CharT, encoding_char_traits< _CharT > >, std::basic_filebuf< _CharT, std::char_traits< _CharT > >, std::basic_filebuf< char_type, traits_type >, and std::basic_stringbuf< _CharT, _Traits, _Alloc >.

Definition at line 692 of file streambuf.

template<typename _CharT , typename _Traits > streamsize std::basic_streambuf< _CharT, _Traits >::xsgetn (char_type * __s, streamsize __n) [protected], [virtual]

Multiple character extraction.

Parameters

Returns

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 in std::basic_filebuf< _CharT, _Traits >, std::basic_filebuf< _CharT, encoding_char_traits< _CharT > >, std::basic_filebuf< _CharT, std::char_traits< _CharT > >, and std::basic_filebuf< char_type, traits_type >.

Definition at line 45 of file streambuf.tcc.

References std::min().

template<typename _CharT , typename _Traits > streamsize std::basic_streambuf< _CharT, _Traits >::xsputn (const char_type * __s, streamsize __n) [protected], [virtual]

Multiple character insertion.

Parameters

Returns

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 in std::basic_filebuf< _CharT, _Traits >, std::basic_filebuf< _CharT, encoding_char_traits< _CharT > >, std::basic_filebuf< _CharT, std::char_traits< _CharT > >, and std::basic_filebuf< char_type, traits_type >.

Definition at line 79 of file streambuf.tcc.

References std::min().

template<typename _CharT , typename _Traits > streamsize __copy_streambufs_eof (basic_streambuf< _CharT, _Traits > * __sbin, basic_streambuf< _CharT, _Traits > * __sbout, bool & __ineof) [friend]

Definition at line 116 of file streambuf.tcc.

template<typename _CharT , typename _Traits > friend class basic_ios< char_type, traits_type > [friend]

Definition at line 140 of file streambuf.

template<typename _CharT , typename _Traits > friend class basic_istream< char_type, traits_type > [friend]

Definition at line 140 of file streambuf.

template<typename _CharT , typename _Traits > friend class basic_ostream< char_type, traits_type > [friend]

Definition at line 140 of file streambuf.

template<typename _CharT , typename _Traits > friend class istreambuf_iterator< char_type, traits_type > [friend]

Definition at line 140 of file streambuf.

template<typename _CharT , typename _Traits > friend class ostreambuf_iterator< char_type, traits_type > [friend]

Definition at line 140 of file streambuf.

template<typename _CharT , typename _Traits > locale std::basic_streambuf< _CharT, _Traits >::_M_buf_locale [protected]

Current locale setting.

Definition at line 197 of file streambuf.

template<typename _CharT , typename _Traits > char_type* std::basic_streambuf< _CharT, _Traits >::_M_in_beg [protected]

Start of get area.

Definition at line 189 of file streambuf.

template<typename _CharT , typename _Traits > char_type* std::basic_streambuf< _CharT, _Traits >::_M_in_cur [protected]

Current read area.

Definition at line 190 of file streambuf.

template<typename _CharT , typename _Traits > char_type* std::basic_streambuf< _CharT, _Traits >::_M_in_end [protected]

End of get area.

Definition at line 191 of file streambuf.

template<typename _CharT , typename _Traits > char_type* std::basic_streambuf< _CharT, _Traits >::_M_out_beg [protected]

Start of put area.

Definition at line 192 of file streambuf.

template<typename _CharT , typename _Traits > char_type* std::basic_streambuf< _CharT, _Traits >::_M_out_cur [protected]

Current put area.

Definition at line 193 of file streambuf.

template<typename _CharT , typename _Traits > char_type* std::basic_streambuf< _CharT, _Traits >::_M_out_end [protected]

End of put area.

Definition at line 194 of file streambuf.