std::basic_ospanstream(3)

💖 NAME 💖

• std::basic_ospanstream — std::basic_ospanstream
• Manual name: std::basic_ospanstream(3) from the C++ Standard Libary, bestie 🫶

✨ Synopsis ✨

Okay so first things first: it's defined in header <spanstream>, and the template situation is literally this:

template<
    class CharT,
    class Traits = std::char_traits<CharT>  (since C++23)
> class basic_ospanstream
    : public basic_ostream<CharT, Traits>

The class template std::basic_ospanstream is the one that implements output operations on streams based on fixed buffers. Slay.

At the low level, this class essentially wraps a raw device implementation of std::basic_spanbuf into a higher-level interface of std::basic_ostream. The complete interface to unique std::basic_spanbuf members is provided — no crumbs, full access, periodt.

std-basic ospanstream-inheritance.svg — Inheritance diagram 🦋

Several typedefs for common character types are provided, and yes they're defined in header <spanstream> too:

• std::ospanstream — std::basic_ospanstream<char>
• std::wospanstream — std::basic_ospanstream<wchar_t>

🎀 Member types 🎀

• char_type — CharT
• traits_type — Traits; the program is ill-formed if Traits::char_type is not CharT.
• int_type — Traits::int_type
• pos_type — Traits::pos_type
• off_type — Traits::off_type

🌸 Data members 🌸

• sb (private) — the wrapped std::basic_spanbuf. (exposition-only member object*)

💅 Member functions 💅

• constructor (C++23) — constructs the basic_ospanstream (public member function)
• destructor [virtual] (C++23) — destroys the basic_ospanstream (virtual public member function)
• operator= (C++23) — move-assignments the basic_ospanstream (public member function)
• swap (C++23) — swaps two basic_ospanstream objects (public member function)
• rdbuf (C++23) — obtains the address of the wrapped raw span device object (public member function)

🧚 Underlying buffer operations 🧚

• span (C++23) — gets or sets the underlying buffer of the wrapped span device object (public member function)

🔥 Non-member functions 🔥

• std::swap(std::basic_ospanstream) — specializes the std::swap algorithm (C++23) (function template)

🌈 Inherited from std::basic_ostream 🌈

👑 Member functions 👑

Formatted output

• operator<< — inserts formatted data (public member function of std::basic_ostream<CharT,Traits>)

Unformatted output

• put — inserts a character (public member function of std::basic_ostream<CharT,Traits>)
• write — inserts blocks of characters (public member function of std::basic_ostream<CharT,Traits>)

Positioning

• tellp — returns the output position indicator (public member function of std::basic_ostream<CharT,Traits>)
• seekp — sets the output position indicator (public member function of std::basic_ostream<CharT,Traits>)

Miscellaneous

• flush — synchronizes with the underlying storage device (public member function of std::basic_ostream<CharT,Traits>)

🦋 Member classes 🦋

• sentry — implements basic logic for preparation of the stream for output operations (public member class of std::basic_ostream<CharT,Traits>)

💜 Inherited from std::basic_ios 💜

✨ Member types ✨

• char_type — CharT
• traits_type — Traits
• int_type — Traits::int_type
• pos_type — Traits::pos_type
• off_type — Traits::off_type

🎀 Member functions 🎀

State functions

• good — checks if no error has occurred i.e. I/O operations are available (public member function of std::basic_ios<CharT,Traits>)
• eof — checks if end-of-file has been reached (public member function of std::basic_ios<CharT,Traits>)
• fail — checks if an error has occurred (public member function of std::basic_ios<CharT,Traits>)
• bad — checks if a non-recoverable error has occurred (public member function of std::basic_ios<CharT,Traits>)
• operator! — checks if an error has occurred (synonym of fail()) (public member function of std::basic_ios<CharT,Traits>)
• operator bool — checks if no error has occurred (synonym of !fail()) (public member function of std::basic_ios<CharT,Traits>)
• rdstate — returns state flags (public member function of std::basic_ios<CharT,Traits>)
• setstate — sets state flags (public member function of std::basic_ios<CharT,Traits>)
• clear — modifies state flags (public member function of std::basic_ios<CharT,Traits>)

Formatting

• copyfmt — copies formatting information (public member function of std::basic_ios<CharT,Traits>)
• fill — manages the fill character (public member function of std::basic_ios<CharT,Traits>)

Miscellaneous

• exceptions — manages exception mask (public member function of std::basic_ios<CharT,Traits>)
• imbue — sets the locale (public member function of std::basic_ios<CharT,Traits>)
• rdbuf — manages associated stream buffer (public member function of std::basic_ios<CharT,Traits>)
• tie — manages tied stream (public member function of std::basic_ios<CharT,Traits>)
• narrow — narrows characters (public member function of std::basic_ios<CharT,Traits>)
• widen — widens characters (public member function of std::basic_ios<CharT,Traits>)

🫶 Inherited from std::ios_base 🫶

💖 Member functions 💖

Formatting

• flags — manages format flags (public member function of std::ios_base)
• setf — sets specific format flag (public member function of std::ios_base)
• unsetf — clears specific format flag (public member function of std::ios_base)
• precision — manages decimal precision of floating point operations (public member function of std::ios_base)
• width — manages field width (public member function of std::ios_base)

Locales

• imbue — sets locale (public member function of std::ios_base)
• getloc — returns current locale (public member function of std::ios_base)

Internal extensible array

• xalloc [static] — returns a program-wide unique integer that is safe to use as index to pword() and iword() (public static member function of std::ios_base)
• iword — resizes the private storage if necessary and access to the long element at the given index (public member function of std::ios_base)
• pword — resizes the private storage if necessary and access to the void* element at the given index (public member function of std::ios_base)

Miscellaneous

• register_callback — registers event callback function (public member function of std::ios_base)
• sync_with_stdio [static] — sets whether C++ and C I/O libraries are interoperable (public static member function of std::ios_base)

🌟 Member classes 🌟

• failure — stream exception (public member class of std::ios_base)
• Init — initializes standard stream objects (public member class of std::ios_base)

✨ Member types and constants ✨

okay bestie, this is the type-and-constant lineup, and it's genuinely a lot 💅 no cap, every single one matters, so let's go.

openmode (typedef) — stream open mode type

The following constants are also defined:

• app — seek to the end of stream before each write
• binary — open in binary mode
• in — open for reading
• out — open for writing
• trunc — discard the contents of the stream when opening
• ate — seek to the end of stream immediately after open
• noreplace (C++23) — open in exclusive mode

---

fmtflags (typedef) — formatting flags type

The following constants are also defined:

• dec — use decimal base for integer I/O: see std::dec
• oct — use octal base for integer I/O: see std::oct
• hex — use hexadecimal base for integer I/O: see std::hex
• basefield — dec | oct | hex. Useful for masking operations
• left — left adjustment (adds fill characters to the right): see std::left
• right — right adjustment (adds fill characters to the left): see std::right
• internal — internal adjustment (adds fill characters to the internal designated point): see std::internal
• adjustfield — left | right | internal. Useful for masking operations
• scientific — generate floating point types using scientific notation, or hex notation if combined with fixed: see std::scientific
• fixed — generate floating point types using fixed notation, or hex notation if combined with scientific: see std::fixed
• floatfield — scientific | fixed. Useful for masking operations
• boolalpha — insert and extract bool type in alphanumeric format: see std::boolalpha
• showbase — generate a prefix indicating the numeric base for integer output, require the currency indicator in monetary I/O: see std::showbase
• showpoint — generate a decimal-point character unconditionally for floating-point number output: see std::showpoint
• showpos — generate a + character for non-negative numeric output: see std::showpos
• skipws — skip leading whitespace before certain input operations: see std::skipws
• unitbuf — flush the output after each output operation: see std::unitbuf
• uppercase — replace certain lowercase letters with their uppercase equivalents in certain output operations: see std::uppercase

---

iostate (typedef) — state of the stream type

The following constants are also defined:

• goodbit — no error
• badbit — irrecoverable stream error
• failbit — input/output operation failed (formatting or extraction error)
• eofbit — associated input sequence has reached end-of-file

---

seekdir (typedef) — seeking direction type

The following constants are also defined:

• beg — the beginning of a stream
• end — the ending of a stream
• cur — the current position of stream position indicator

---

event (enum) — specifies event type

event_callback (typedef) — callback function type

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📝 Notes 📝

Feature-test macro time, bestie — this is the little receipt that tells you the feature exists:

• Feature-test macro: __cpp_lib_spanstream
• Value: 202106L
• Std: (C++23)
• Feature: std::spanbuf, std::spanstream

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That's the whole vibe check, bestie 🫶 page source is cppreference.com, source/version date is 2024.06.10, and this iconic little manual page is std::basic_ospanstream(3). Stay slay, keep your streams safe, and may your flags always be exactly where you left them 💅✨