std::basic_osyncstream(3) C++ Standard Libary std::basic_osyncstream(3) NAME std::basic_osyncstream - std::basic_osyncstream Synopsis Defined in header <syncstream> template< class CharT, class Traits = std::char_traits<CharT>, (since C++20) class Allocator = std::allocator<CharT> > class basic_osyncstream : public std::basic_ostream<CharT, Traits> The class template std::basic_osyncstream is a convenience wrapper for std::basic_syncbuf. It provides a mechanism to synchronize threads writ- ing to the same stream. It can be used with a named variable: { std::osyncstream synced_out(std::cout); // synchronized wrapper for std::cout synced_out << "Hello, "; synced_out << "World!"; synced_out << std::endl; // flush is noted, but not yet performed synced_out << "and more!\n"; } // characters are transferred and std::cout is flushed as well as with a temporary: std::osyncstream(std::cout) << "Hello, " << "World!" << '\n'; It provides the guarantee that all output made to the same final desti- nation buffer (std::cout in the examples above) will be free of data races and will not be interleaved or garbled in any way, as long as every write to that final destination buffer is made through (possibly different) instances of std::ba- sic_osyncstream. Typical implementation of std::basic_osyncstream holds only one member: the wrapped std::basic_syncbuf. std-basic osyncstream-inheritance.svg Inheritance diagram Several typedefs for common character types are provided: Defined in header <syncstream> Type Definition std::osyncstream std::basic_osyncstream<char> std::wosyncstream std::basic_osyncstream<wchar_t> Member types Member type Definition 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 allocator_type Allocator streambuf_type std::basic_streambuf<CharT, Traits> syncbuf_type std::basic_syncbuf<CharT, Traits, Allocator> Member functions constructor constructs a basic_osyncstream object (public member function) operator= assigns a basic_osyncstream object (public member function) destructor destroys the basic_osyncstream and emits its internal buffer (public member function) rdbuf obtains a pointer to the underlying basic_syncbuf (public member function) get_wrapped obtains a pointer to the final destination stream buffer (public member function) calls emit() on the underlying basic_syncbuf to transmit its internal emit data to the final destination (public member function) 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 Member type Definition 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 returns a program-wide unique integer that is safe to use as index [static] to pword() and iword() (public static member function of std::ios_base) resizes the private storage if necessary and access to the long iword element at the given index (public member function of std::ios_base) resizes the private storage if necessary and access to the void* pword 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 sets whether C++ and C I/O libraries are interoperable [static] (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 Type Explanation stream open mode type The following constants are also defined: Constant Explanation app seek to the end of stream before each write binary open in binary mode openmode 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 (typedef) formatting flags type The following constants are also defined: Constant Explanation 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 opera- tions 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 generate floating point types using scien- tific notation, scientific or hex notation if combined with fixed: see std::scientific fmtflags generate floating point types using fixed no- tation, or fixed hex notation if combined with scientific: see std::fixed floatfield scientific | fixed. Useful for masking opera- tions boolalpha insert and extract bool type in alphanumeric format: see std::boolalpha generate a prefix indicating the numeric base for integer showbase output, require the currency indicator in monetary I/O: see std::showbase showpoint generate a decimal-point character uncondi- tionally for floating-point number output: see std::show- point showpos generate a + character for non-negative nu- meric 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 replace certain lowercase letters with their uppercase uppercase equivalents in certain output operations: see std::uppercase (typedef) state of the stream type The following constants are also defined: Constant Explanation iostate goodbit no error badbit irrecoverable stream error failbit input/output operation failed (formatting or ex- traction error) eofbit associated input sequence has reached end-of- file (typedef) seeking direction type The following constants are also defined: seekdir Constant Explanation beg the beginning of a stream end the ending of a stream cur the current position of stream position indica- tor (typedef) event specifies event type (enum) event_callback callback function type (typedef) Notes Feature-test macro Value Std Feature __cpp_lib_syncbuf 201803L (C++20) Synchronized buffered ostream (std::osyncstream, std::syncbuf) and manipulators http://cppreference.com 2024.06.10 std::basic_osyncstream(3)
NAME | Synopsis | Member types | Member functions | Member functions | Formatted output | Unformatted output | Positioning | Miscellaneous | Member classes | Member types | Member functions | State functions | Formatting | Miscellaneous | Member functions | Formatting | Locales | Internal extensible array | Miscellaneous | Member classes | Member types and constants | Notes
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