Section 3: library functions
std::ios_base::xalloc – std::ios_base::xalloc Synopsis static int xalloc(); Returns a unique (program-wide) index value that can be used to access one long and one void* elements in the private storage of std::ios_base by calling iword() and pword(). The call to xalloc does not allocate memory. This function is thread-safe; concurrent access by multiple threads does not…
std::ios_base::width – std::ios_base::width Synopsis streamsize width() const; (1) streamsize width( streamsize new_width ); (2) Manages the minimum number of characters to generate on certain output operations and the maximum number of characters to generate on certain input operations. 1) Returns the current field width. 2) Sets the field width to the given one. Returns the…
std::ios_base::unsetf – std::ios_base::unsetf Synopsis void unsetf(fmtflags flags); Unsets the formatting flags identified by flags. Parameters formatting flags to unset. It can be a combination of the following constants: 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:…
std::ios_base::sync_with_stdio – std::ios_base::sync_with_stdio Synopsis static bool sync_with_stdio( bool sync = true ); Sets whether the standard C++ streams are synchronized to the standard C streams after each input/output operation. The standard C++ streams are the following: std::cin, std::cout, std::cerr, std::clog, std::wcin, std::wcout, std::wcerr and std::wclog The standard C streams are the following: stdin, stdout and…
std::ios_base::setf – std::ios_base::setf Synopsis fmtflags setf( fmtflags flags ); (1) fmtflags setf( fmtflags flags, fmtflags mask ); (2) Sets the formatting flags to specified settings. 1) Sets the formatting flags identified by flags. Effectively the following operation is performed fl = fl | flags where fl defines the state of internal formatting flags. 2) Clears…
std::ios_base::seekdir – std::ios_base::seekdir Synopsis typedef /*implementation defined*/ seekdir; static constexpr seekdir beg = /*implementation defined*/ static constexpr seekdir end = /*implementation defined*/ static constexpr seekdir cur = /*implementation defined*/ Specifies file seeking direction type. The following constants are defined: Constant Explanation beg the beginning of a stream end the ending of a stream cur the…
std::ios_base::register_callback – std::ios_base::register_callback Synopsis void register_callback(event_callback function, int index); Registers a user-defined function which will be called by imbue(), std::basic_ios::copyfmt() and ~ios_base(). Every registered callback is called every time: the event type (a value of type event) is passed as its first argument, and may be used to distinguish between the callers. The callbacks are…
std::ios_base::pword – std::ios_base::pword Synopsis void *&pword(int index); First, allocates or resizes the private storage (dynamic array of void* or another indexable data structure) sufficiently to make index a valid index, then returns a reference to the void* element of the private storage with the index index. The reference may be invalidated by any operation on…
std::ios_base::precision – std::ios_base::precision Synopsis streamsize precision() const; (1) streamsize precision( streamsize new_precision ); (2) Manages the precision (i.e. how many digits are generated) of floating point output performed by std::num_put::do_put. 1) Returns the current precision. 2) Sets the precision to the given one. Returns the previous precision. The default precision, as established by std::basic_ios::init, is…
std::ios_base::openmode – std::ios_base::openmode Synopsis typedef /*implementation defined*/ openmode; static constexpr openmode app = /*implementation defined*/ static constexpr openmode binary = /*implementation defined*/ static constexpr openmode in = /*implementation defined*/ static constexpr openmode out = /*implementation defined*/ static constexpr openmode trunc = /*implementation defined*/ static constexpr openmode ate = /*implementation defined*/ Specifies available file open flags….
std::ios_base::iword – std::ios_base::iword Synopsis long &iword(int index); First, allocates or resizes the private storage (dynamic array of long or another indexable data structure) sufficiently to make index a valid index, then returns a reference to the long element of the private storage with the index index. The reference may be invalidated by any operation on…
std::ios_base::iostate – std::ios_base::iostate Synopsis typedef /*implementation defined*/ iostate; static constexpr iostate goodbit = 0; static constexpr iostate badbit = /*implementation defined*/ static constexpr iostate failbit = /*implementation defined*/ static constexpr iostate eofbit = /*implementation defined*/ Specifies stream state flags. It is a BitmaskType, the following constants are defined: Constant Explanation goodbit no error badbit irrecoverable…
std::ios_base::~ios_base – std::ios_base::~ios_base Synopsis virtual ~ios_base(); Destroys the ios_base object. Before any of the member functions would yield undefined results, calls callbacks, registered by register_callback() passing erase_event as parameter. No operations on rdbuf are performed, it is not destroyed.
std::ios_base::imbue – std::ios_base::imbue Synopsis std::locale imbue(const std::locale &loc); Sets the associated locale of the stream to the given one. Before returning, each function, registered by register_callback() is called with imbue_event as a parameter. Parameters loc – new locale to associate the stream to Return value The locale object, associated with the stream before the operation…
std::ios_base::getloc – std::ios_base::getloc Synopsis std::locale getloc() const; Returns the current locale associated with the stream. Parameters (none) Return value the locale object associated with the stream. Example // Run this code #include <iostream> #include <ctime> #include <iomanip> #include <codecvt> int main() { std::wbuffer_convert<std::codecvt_utf8<wchar_t>> conv(std::cout.rdbuf()); std::wostream out(&conv); out.imbue(std::locale(out.getloc(), new std::time_put_byname<wchar_t>("ja_JP"))); std::time_t t = std::time(NULL); out <<…
std::ios_base::fmtflags – std::ios_base::fmtflags Synopsis typedef /*implementation defined*/ fmtflags; static constexpr fmtflags dec = /*implementation defined*/ static constexpr fmtflags oct = /*implementation defined*/ static constexpr fmtflags hex = /*implementation defined*/ static constexpr fmtflags basefield = dec | oct | hex; static constexpr fmtflags left = /*implementation defined*/ static constexpr fmtflags right = /*implementation defined*/ static constexpr…
std::ios_base::flags – std::ios_base::flags Synopsis fmtflags flags() const; (1) fmtflags flags( fmtflags flags ); (2) Manages format flags. 1) returns current formatting setting 2) replaces current settings with given ones. Parameters new formatting setting. It can be a combination of the following constants: Constant Explanation dec use decimal base for integer I/O: see std::dec oct use…
std::ios_base::failure – std::ios_base::failure Synopsis Defined in header <ios> class failure; The class std::ios_base::failure defines an exception object that is thrown on failure by the functions in the Input/Output library. std::ios_base::failure may be defined either as a member class of std::ios_base or as a synonym (typedef) for another class with equivalent functionality. (since C++17) std-ios base-failure-2003-inheritance.svg…
std::ios_base::event_callback – std::ios_base::event_callback Synopsis typedef void (*event_callback)(event type, ios_base &ios, int index); The type of function callbacks that can be registered using register_callback() to be called on specific events. type is a value of type ios_base::event which indicates the type of the event that will invoke this callback. ios refers to the stream object for…
std::ios_base::event – std::ios_base::event Synopsis enum event {erase_event, imbue_event, copyfmt_event}; Specifies the event type which is passed to functions registered by register_callback() on specific events. The following constants are defined: Constant Explanation erase_event issued on ~ios_base() or basic_ios::copyfmt() (before the copy of members takes place) imbue_event issued on imbue() copyfmt_event issued on basic_ios::copyfmt() (after the copy…