Provided by: libstdc++-13-doc_13.2.0-23ubuntu4_all bug

NAME

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

SYNOPSIS

       #include <streambuf>

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

   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 >

Detailed Description

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

       Template Parameters
           _CharT Type of character stream.
           _Traits Traits for character type, defaults to char_traits<_CharT>.

       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).

Member Typedef Documentation

   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.

   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.

   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.

   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.

   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.

   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.

Constructor & Destructor Documentation

   template<typename _CharT , typename _Traits > virtual std::basic_streambuf< _CharT, _Traits
       >::~basic_streambuf () [inline],  [virtual]
       Destructor deallocates no buffer space.

   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

Member Function Documentation

   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

   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

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

   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

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

       Parameters
           __n The delta by which to move.

       This just advances the read position without returning any data.

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

   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

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

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

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

   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
           __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 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
           Base class version does nothing, returns eof().

       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 >, __gnu_cxx::stdio_sync_filebuf< _CharT,
       _Traits >, std::basic_stringbuf< _CharT, _Traits, _Alloc >, and std::wbuffer_convert<
       _Codecvt, _Elem, _Tr >.

   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
           __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 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 >, __gnu_cxx::stdio_sync_filebuf< _CharT,
       _Traits >, and std::basic_stringbuf< _CharT, _Traits, _Alloc >.

   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

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

       Parameters
           __n The delta by which to move.

       This just advances the write position without returning any data.

   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

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

       Parameters
           __loc The new locale.

       Returns
           The previous locale.

       Calls the derived imbue(__loc).

   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
           __off Offset.
           __way Value for ios_base::seekdir.
           __mode Value for ios_base::openmode.

       Calls virtual seekoff function.

   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
           __sp Position
           __mode Value for ios_base::openmode.

       Calls virtual seekpos function.

   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.

   template<typename _CharT , typename _Traits > int std::basic_streambuf< _CharT, _Traits
       >::pubsync () [inline]
       Calls virtual sync function.

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

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

       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 >.

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

       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 >.

   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
           Base class version does nothing, returns this.

       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 >.

   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
           __gbeg A pointer.
           __gnext A pointer.
           __gend A pointer.

       Postcondition
           __gbeg == eback(), __gnext == gptr(), and __gend == egptr()

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

   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
           __pbeg A pointer.
           __pend A pointer.

       Postcondition
           __pbeg == pbase(), __pbeg == pptr(), and __pend == epptr()

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

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

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

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

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

   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
           __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.

   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
           __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).

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

   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
           __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.

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

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

   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
           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 >.

   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
           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 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
           Base class version does nothing, returns eof().

       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 >.

   template<typename _CharT , typename _Traits > streamsize std::basic_streambuf< _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 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 >.

       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
           __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 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 >.

       References std::min().

Member Data Documentation

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

       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]
       Start of get area.

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

   template<typename _CharT , typename _Traits > char_type* std::basic_streambuf< _CharT, _Traits
       >::_M_in_end [protected]
       End of get area.

   template<typename _CharT , typename _Traits > char_type* std::basic_streambuf< _CharT, _Traits
       >::_M_out_beg [protected]
       Start of put area.

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

   template<typename _CharT , typename _Traits > char_type* std::basic_streambuf< _CharT, _Traits
       >::_M_out_end [protected]
       End of put area.

Author

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