__GNU_CXX::STDIO_SYNC_FILEBUF(3)

💖 __gnu_cxx::stdio_sync_filebuf< _CharT, _Traits > 💖

Library Functions Manual — section 3! Welcome to the group chat, bestie 💅. This page is all about __gnu_cxx::stdio_sync_filebuf< _CharT, _Traits >, and we're gonna spill every single tea ☕.

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✨ NAME ✨

• __gnu_cxx::stdio_sync_filebuf< _CharT, _Traits > — Provides a layer of compatibility for C. 🫶

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🌸 SYNOPSIS 🌸

#include <stdio_sync_filebuf.h>

Inherits std::basic_streambuf< _CharT, _Traits >. 👑

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🎀 Public Types 🎀

• 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

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💅 Public Member Functions 💅

• stdio_sync_filebuf (std::__c_file *__f)
• stdio_sync_filebuf (stdio_sync_filebuf &&__fb) noexcept
• std::__c_file * file ()
• locale getloc () const — Locale access.
• streamsize in_avail () — Looking ahead into the stream.
• stdio_sync_filebuf & operator= (stdio_sync_filebuf &&__fb) noexcept
• 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.
• void swap (stdio_sync_filebuf &__fb)
• 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.

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🧚 Protected Member Functions 🧚

• 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.
• 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 std::streampos seekoff (std::streamoff __off, std::ios_base::seekdir __dir, std::ios_base::openmode=std::ios_base::in|std::ios_base::out)
• virtual pos_type seekoff (off_type, ios_base::seekdir, ios_base::openmode=ios_base::in|ios_base::out) — Alters the stream positions.
• virtual std::streampos seekpos (std::streampos __pos, std::ios_base::openmode __mode=std::ios_base::in|std::ios_base::out)
• 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.
• stdio_sync_filebuf< wchar_t >::int_type syncgetc ()
• stdio_sync_filebuf< char >::int_type syncgetc ()
• int_type syncgetc ()
• stdio_sync_filebuf< wchar_t >::int_type syncputc (int_type __c)
• stdio_sync_filebuf< char >::int_type syncputc (int_type __c)
• int_type syncputc (int_type __c)
• stdio_sync_filebuf< wchar_t >::int_type syncungetc (int_type __c)
• stdio_sync_filebuf< char >::int_type syncungetc (int_type __c)
• int_type syncungetc (int_type __c)
• virtual int_type uflow () — Fetches more data from the controlled sequence.
• virtual int_type underflow () — Fetches more data from the controlled sequence.
• std::streamsize xsgetn (char *__s, std::streamsize __n)
• virtual std::streamsize xsgetn (char_type *__s, std::streamsize __n)
• std::streamsize xsgetn (wchar_t *__s, std::streamsize __n)
• virtual streamsize xsgetn (char_type *__s, streamsize __n) — Multiple character extraction.
• std::streamsize xsputn (const char *__s, std::streamsize __n)
• virtual std::streamsize xsputn (const char_type *__s, std::streamsize __n)
• std::streamsize xsputn (const wchar_t *__s, std::streamsize __n)
• 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.

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🍓 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.

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💫 Detailed Description 💫

template<typename _CharT, typename _Traits = std::char_traits<_CharT>>
class __gnu_cxx::stdio_sync_filebuf< _CharT, _Traits >

Provides a layer of compatibility for C. ✨

This GNU extension provides extensions for working with standard C FILE*'s. It must be instantiated by the user with the type of character used in the file stream, e.g., stdio_filebuf<char>. 💖

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📚 Member Function Documentation 📚

🌟 eback() 🌟

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

Referenced by std::basic_filebuf< char_type, traits_type >::_M_destroy_pback(), std::basic_filebuf< _CharT, _Traits >::imbue(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::overflow(), std::basic_filebuf< _CharT, _Traits >::pbackfail(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::pbackfail(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::seekoff(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::seekpos(), std::basic_streambuf< char_type, traits_type >::sputbackc(), std::basic_streambuf< char_type, traits_type >::sungetc(), std::basic_filebuf< _CharT, _Traits >::underflow(), and std::basic_filebuf< _CharT, _Traits >::xsgetn(). 💅

🌟 egptr() 🌟

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

Referenced by std::basic_filebuf< char_type, traits_type >::_M_create_pback(), std::basic_streambuf< char_type, traits_type >::in_avail(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::overflow(), std::basic_streambuf< char_type, traits_type >::sbumpc(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::seekoff(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::seekpos(), std::basic_streambuf< char_type, traits_type >::sgetc(), std::basic_filebuf< _CharT, _Traits >::showmanyc(), std::basic_stringbuf< char >::showmanyc(), std::basic_filebuf< _CharT, _Traits >::underflow(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::underflow(), std::wbuffer_convert< _Codecvt, _Elem, _Tr >::underflow(), std::basic_filebuf< _CharT, _Traits >::xsgetn(), and xsgetn(). 💅

🌟 epptr() 🌟

template<typename _CharT, typename _Traits> char_type *
std::basic_streambuf< _CharT, _Traits >::epptr () 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

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

🌟 file() 🌟

template<typename _CharT, typename _Traits = std::char_traits<_CharT>>
std::__c_file * __gnu_cxx::stdio_sync_filebuf< _CharT, _Traits >::file
() [inline]

• Returns: The underlying FILE*.

This function can be used to access the underlying C file pointer. Note that there is no way for the library to track what you do with the file, so be careful. ⚠️

🌟 gbump() 🌟

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. 🚀

Referenced by std::basic_filebuf< _CharT, _Traits >::pbackfail(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::pbackfail(), std::basic_streambuf< char_type, traits_type >::sbumpc(), std::basic_streambuf< char_type, traits_type >::sputbackc(), std::basic_streambuf< char_type, traits_type >::sungetc(), std::basic_streambuf< char_type, traits_type >::uflow(), and std::basic_filebuf< _CharT, _Traits >::xsgetn(). 💅

🌟 getloc() 🌟

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.

Referenced by std::basic_streambuf< char_type, traits_type >::pubimbue(). 💅

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💅 gptr() — the get-area glow-up

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. iykyk — it's a members-only situation, bestie 🎀

• 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::basic_filebuf< char_type, traits_type >::_M_create_pback(), std::basic_filebuf< char_type, traits_type >::_M_destroy_pback(), std::basic_filebuf< _CharT, _Traits >::imbue(), std::basic_streambuf< char_type, traits_type >::in_avail(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::overflow(), std::basic_filebuf< _CharT, _Traits >::pbackfail(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::pbackfail(), std::basic_streambuf< char_type, traits_type >::sbumpc(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::seekoff(), std::basic_streambuf< char_type, traits_type >::sgetc(), std::basic_filebuf< _CharT, _Traits >::showmanyc(), std::basic_stringbuf< char >::showmanyc(), std::basic_streambuf< char_type, traits_type >::sputbackc(), std::basic_streambuf< char_type, traits_type >::sungetc(), std::basic_streambuf< char_type, traits_type >::uflow(), std::basic_filebuf< _CharT, _Traits >::underflow(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::underflow(), std::wbuffer_convert< _Codecvt, _Elem, _Tr >::underflow(), std::basic_filebuf< _CharT, _Traits >::xsgetn(), and xsgetn(). (that's a whole friend group right there 😭)

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🦋 imbue() — changing the translations, literally

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

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 > >, std::basic_filebuf< char >, std::basic_filebuf< char_type, traits_type >, and std::basic_filebuf< wchar_t >.

Referenced by std::basic_streambuf< char_type, traits_type >::pubimbue().

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👀 in_avail() — looking ahead into the stream

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

Looking ahead into the stream. Not me peeking at what's coming next 🙈

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(). periodt 💅

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🔥 overflow() — consuming data from the buffer, writing to the controlled sequence

template<typename _CharT, typename _Traits = std::char_traits<_CharT>>
    virtual int_type __gnu_cxx::stdio_sync_filebuf< _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. (yes bestie, they're citing the standard, it's giving academic 📚)

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 >.

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⏪ pbackfail() — trying to back up the input sequence

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

Tries to back up the input sequence. rewinding like it's a voice message you didn't mean to send 😭

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 >.

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✨ pbase() — access to the put area

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. protected squad only 🫶

• 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

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

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🚶‍♀️ pbump() — moving the write position

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. no takebacks, just vibes forward 💅

Referenced by std::basic_filebuf< _CharT, _Traits >::overflow(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::overflow(), and std::basic_streambuf< char_type, traits_type >::sputc().

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🌸 pptr() — also access to the put area

template<typename _CharT, typename _Traits> char_type *
    std::basic_streambuf< _CharT, _Traits >::pptr () 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

Referenced by std::basic_filebuf< _CharT, _Traits >::overflow(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::overflow(), std::basic_filebuf< _CharT, _Traits >::seekoff(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::seekoff(), std::basic_streambuf< char_type, traits_type >::sputc(), std::basic_filebuf< _CharT, _Traits >::sync(), std::basic_filebuf< _CharT, _Traits >::xsputn(), and xsputn().

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🎀 pubimbue() — the entry point for imbue()

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

Entry point for imbue(). the public-facing baddie that passes the job down 💖

Parameters

• __loc — The new locale.

Returns

• The previous locale.

Calls the derived imbue(__loc).

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🧚 pubseekoff() — alters the stream position

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]

Alters the stream position. 💫

Parameters

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

Calls virtual seekoff function.

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🦄 pubseekpos() — also alters the stream position

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]

Alters the stream position. 💫

Parameters

• __sp — Position
• __mode — Value for ios_base::openmode.

Calls virtual seekpos function.

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🍬 pubsetbuf() — entry points for derived buffer functions

template<typename _CharT, typename _Traits> basic_streambuf *
    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. it's giving middle-manager energy but make it virtual ✨

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🔔 pubsync() — calls virtual sync function

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

Calls virtual sync function. sync up bestie, we're committing 💅

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

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💀 sbumpc() — getting the next character

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().

Referenced by std::basic_istream< _CharT, _Traits >::ignore(), std::basic_streambuf< char_type, traits_type >::snextc(), and std::basic_istream< _CharT, char_traits< _CharT > >::unget().

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🌈 seekoff() — alters the stream positions

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],  [inherited]

Alters the stream positions. Each derived class provides its own appropriate behavior. everyone does their own thing, we love autonomy 💖

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< char >, std::basic_filebuf< char_type, traits_type >, std::basic_filebuf< wchar_t >, std::basic_stringbuf< _CharT, _Traits, _Alloc >, std::basic_stringbuf< char >, and std::basic_stringbuf< wchar_t >.

Referenced by std::basic_streambuf< char_type, traits_type >::pubseekoff().

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⭐ seekpos() — also alters the stream positions

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],  [inherited]

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< char >, std::basic_filebuf< char_type, traits_type >, std::basic_filebuf< wchar_t >, std::basic_stringbuf< _CharT, _Traits, _Alloc >, std::basic_stringbuf< char >, and std::basic_stringbuf< wchar_t >.

Referenced by std::basic_streambuf< char_type, traits_type >::pubseekpos().

setbuf 💅

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

[inline], [protected], [virtual], [inherited]

okay so bestie, this one manipulates the buffer and that's literally all the base class is gonna tell you. Every derived class provides its own appropriate behavior — she's giving template-method energy, not implementation energy. Want the lore? Peep the next-to-last paragraph of https://gcc.gnu.org/onlinedocs/libstdc++/manual/streambufs.html#io.streambuf.buffering 🫶

Note — the base class version does absolutely nothing and returns this. no notes, zero effort, still valid. 💀

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>, std::basic_filebuf<char_type, traits_type>, std::basic_stringbuf<_CharT, _Traits, _Alloc>, and std::basic_stringbuf<char>.

Referenced by std::basic_streambuf<char_type, traits_type>::pubsetbuf().

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setg — setting the read area pointers 🌸

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

[inline], [protected], [inherited]

She's setting the three read area pointers. That's the whole job. three pointers, one function, no drama. ✨

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(), std::basic_filebuf<char_type, traits_type>::_M_create_pback(), std::basic_filebuf<char_type, traits_type>::_M_destroy_pback(), std::basic_filebuf<char_type, traits_type>::_M_set_buffer(), std::basic_stringbuf<_CharT, _Traits, _Alloc>::overflow(), std::basic_stringbuf<_CharT, _Traits, _Alloc>::seekoff(), std::basic_stringbuf<_CharT, _Traits, _Alloc>::seekpos(), and std::basic_filebuf<_CharT, _Traits>::xsgetn().

---

setp — the write-area sibling 🎀

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. Yes, three pointers, two arguments — that's not a typo bestie, that's just how she is. 😭

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(), and std::basic_filebuf<char_type, traits_type>::_M_set_buffer().

---

sgetc — getting the next character, peek edition 👀

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

[inline], [inherited]

Getting the next character. A classic.

Returns — the next character, or eof.

so like, if the input read position is available, she returns that character. otherwise she calls and returns underflow(). And here's the important bit: she does not move the read position after fetching. peek don't consume, periodt. 💅

Referenced by std::basic_istream<_CharT, _Traits>::get(), std::basic_istream<_CharT, _Traits>::get(), std::basic_istream<_CharT, _Traits>::ignore(), std::basic_istream<_CharT, char_traits<_CharT>>::readsome(), and std::basic_streambuf<char_type, traits_type>::snextc().

---

sgetn — entry point for xsgetn 🦋

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

[inline], [inherited]

Entry point for xsgetn. she's the front desk, xsgetn is the one doing the actual work.

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.

---

showmanyc — investigating the data available 🔍

template<typename _CharT, typename _Traits>
virtual streamsize std::basic_streambuf<_CharT, _Traits>::showmanyc()

[inline], [protected], [virtual], [inherited]

She's investigating the data available, detective mode fr fr.

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 — the base class version does nothing, returns zero. 😴

Note — 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.

Note — the standard adds that the morphemes of showmanyc are es-how-many-see, not show-manic. iykyk, this is the single most iconic footnote in the whole libstdc++ docs, no cap. 🏆

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>, std::basic_filebuf<char_type, traits_type>, std::basic_filebuf<wchar_t>, std::basic_stringbuf<_CharT, _Traits, _Alloc>, std::basic_stringbuf<char>, and std::basic_stringbuf<wchar_t>.

Referenced by std::basic_streambuf<char_type, traits_type>::in_avail().

---

snextc — getting the next character, again 💜

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

[inline], [inherited]

Getting the next character. (yes, the same one-liner as sgetc, she shares the tagline, it's a whole thing)

Returns — the next character, or eof.

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

Referenced by std::basic_istream<_CharT, char_traits<_CharT>>::get(), std::basic_iostream<char_type, traits_type>::ignore(), and std::basic_istream<_CharT, char_traits<_CharT>>::readsome().

---

sputbackc — pushing characters back into the input stream ⏪

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. like a lil undo button, bestie.

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. ✨

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

---

sputc — entry point for all single-character output functions 🌈

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. THE entry point. all of them. every single one. 👑

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().

---

sputn — entry point for all single-character output functions (yes, again) 🍓

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. Not me noticing the docs gave her the exact same one-liner as sputc even though she's very much a multi-character function... the docs said what they said, and we report the facts. 💀

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.

---

sungetc — moving backwards in the input stream 🔙

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

[inline], [inherited]

Moving backwards in the input stream.</ peach>

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. lowkey the rewind button of the streambuf world. 🫶

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

---

stdio_sync_filebuf::sync — the one that actually lives on this page 👑

template<typename _CharT, typename _Traits = std::char_traits<_CharT>>
virtual int __gnu_cxx::stdio_sync_filebuf<_CharT, _Traits>::sync()

[inline], [protected], [virtual]

Synchronizes the buffer arrays with the controlled sequences. yes bestie, we finally made it to the class in the title of the whole manpage. main character energy. ✨

Returns — -1 on failure.

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

Note — the base class version does nothing, returns zero. she's not even trying and honestly? respect. 😭

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

---

stdio_sync_filebuf::uflow — fetches more data 📥

template<typename _CharT, typename _Traits = std::char_traits<_CharT>>
virtual int_type __gnu_cxx::stdio_sync_filebuf<_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. so she's underflow() with commitment issues — she actually moves on. 💅

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

---

stdio_sync_filebuf::underflow — the O.G. 📥

template<typename _CharT, typename _Traits = std::char_traits<_CharT>>
virtual int_type __gnu_cxx::stdio_sync_filebuf<_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. (yes bestie, they're telling you to go read a book. iconic.)

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 — the base class version does nothing, returns eof(). 💀

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

---

xsgetn — multiple character extraction 🎀

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

[protected], [virtual], [inherited]

Multiple character extraction. bulk mode, activated.

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. (a.k.a. "this base version works but she's giving minimum viable product, please upgrade.") ✨

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>, and std::basic_filebuf<char_type, traits_type>.

References egptr(), gptr(), std::min(), and uflow().

Referenced by std::basic_streambuf<char_type, traits_type>::sgetn().

---

xsputn — multiple character insertion 📤

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

[protected], [virtual], [inherited]

Multiple character insertion.

Parameters 💖

• __s — a buffer area, bestie. like, the lil chunk of memory where the chars live 🌸
• __n — the maximum number of characters to write. that's the ceiling, not a suggestion 🎀

Returns 🌟

The number of characters written. fr fr, that's what you get back.

---

okay so what it actually does: it writes __s[0] through __s[__n-1] to the output sequence, as if by sputc(). it stops when either n characters have been copied, or when sputc() would return traits::eof(). like it just pulls the plug the second things go sideways 😭

it is expected that derived classes provide a more efficient implementation by overriding this definition. so yeah, the base version is giving "we'll do it live" energy — the derived classes are supposed to come in and slay it properly 👑

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 >, and std::basic_filebuf< char_type, traits_type >. five whole glow-ups, we love to see it 💅

References epptr(), std::min(), overflow(), and pptr().

Referenced by std::basic_streambuf< char_type, traits_type >::sputn().

---

✨ Member Data Documentation ✨

these are all [protected] and [inherited], so they're like... the family secrets of std::basic_streambuf< _CharT, _Traits >. you don't touch them from outside, but inside? iconic. 🦋

🌸 _M_buf_locale

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

Current locale setting. that's the vibe check for your character encoding, bestie 🌈

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

🎀 _M_in_beg

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

Start of get area. the beginning of the read zone, periodt.

💜 _M_in_cur

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

Current read area. this is where you're at right now — main character energy, always present 🫶

🦋 _M_in_end

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

End of get area. the read area said "this is my last straw" ✋

🍓 _M_out_beg

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

Start of put area. the write zone begins here, no cap.

⭐ _M_out_cur

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

Current put area. where the writing is happening at this exact moment 😌

🌈 _M_out_end

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

End of put area. the put area's final boss / boundary. past here? not it 🚫

---

💅 Author 💅

Generated automatically by Doxygen for libstdc++ from the source code. not a human, not a girlboss, just a doc generator doing its lil thing 🤖✨

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and that's the whole page, bestie!! 🎉 this came from the libstdc++ crew — that's the source and version, and the page name is __gnu_cxx:... _Traits >(3) — and it's all dated whenever Doxygen last ran its little generator, iykyk. go forth and buffer responsibly 💖🌸🦋