std_ios_base.3cxx

Langue: en

Version: 349857 (ubuntu - 24/10/10)

Section: 3 (Bibliothèques de fonctions)

Sommaire

NAME

std::ios_base -

The base of the I/O class hierarchy.

This class defines everything that can be defined about I/O that does not depend on the type of characters being input or output. Most people will only see ios_base when they need to specify the full name of the various I/O flags (e.g., the openmodes).

SYNOPSIS


Inherited by std::basic_ios< char, _Traits >, and std::basic_ios< _CharT, _Traits >.

Classes


class failure
These are thrown to indicate problems with io.

27.4.2.1.1 Class ios_base::failure. "

Public Types


enum event { erase_event, imbue_event, copyfmt_event }

typedef void(* event_callback )(event, ios_base &, int)

typedef _Ios_Fmtflags fmtflags

typedef int io_state

typedef _Ios_Iostate iostate

typedef int open_mode

typedef _Ios_Openmode openmode

typedef int seek_dir

typedef _Ios_Seekdir seekdir

typedef std::streamoff streamoff

typedef std::streampos streampos

Public Member Functions


virtual ~ios_base ()

const locale & _M_getloc () const

fmtflags flags () const

fmtflags flags (fmtflags __fmtfl)

locale getloc () const

locale imbue (const locale &__loc) throw ()

long & iword (int __ix)

streamsize precision (streamsize __prec)

streamsize precision () const

void *& pword (int __ix)

void register_callback (event_callback __fn, int __index)

fmtflags setf (fmtflags __fmtfl)

fmtflags setf (fmtflags __fmtfl, fmtflags __mask)

void unsetf (fmtflags __mask)

streamsize width () const

streamsize width (streamsize __wide)

Static Public Member Functions


static bool sync_with_stdio (bool __sync=true)

static int xalloc () throw ()

Static Public Attributes


static const fmtflags adjustfield

static const openmode app

static const openmode ate

static const iostate badbit

static const fmtflags basefield

static const seekdir beg

static const openmode binary

static const fmtflags boolalpha

static const seekdir cur

static const fmtflags dec

static const seekdir end

static const iostate eofbit

static const iostate failbit

static const fmtflags fixed

static const fmtflags floatfield

static const iostate goodbit

static const fmtflags hex

static const openmode in

static const fmtflags internal

static const fmtflags left

static const fmtflags oct

static const openmode out

static const fmtflags right

static const fmtflags scientific

static const fmtflags showbase

static const fmtflags showpoint

static const fmtflags showpos

static const fmtflags skipws

static const openmode trunc

static const fmtflags unitbuf

static const fmtflags uppercase

Protected Types


enum { _S_local_word_size }

Protected Member Functions


void _M_call_callbacks (event __ev) throw ()

void _M_dispose_callbacks (void) throw ()

_Words & _M_grow_words (int __index, bool __iword)

void _M_init () throw ()

Protected Attributes


_Callback_list * _M_callbacks

iostate _M_exception

fmtflags _M_flags

locale _M_ios_locale

_Words _M_local_word [_S_local_word_size]

streamsize _M_precision

iostate _M_streambuf_state

streamsize _M_width

_Words * _M_word

int _M_word_size

_Words _M_word_zero

Detailed Description

The base of the I/O class hierarchy.

This class defines everything that can be defined about I/O that does not depend on the type of characters being input or output. Most people will only see ios_base when they need to specify the full name of the various I/O flags (e.g., the openmodes).

Definition at line 207 of file ios_base.h.

Member Typedef Documentation

typedef void(* std::ios_base::event_callback)(event, ios_base &, int)

The type of an event callback function. Parameters:

event One of the members of the event enum.
ios_base Reference to the ios_base object.
int The integer provided when the callback was registered.

Event callbacks are user defined functions that get called during several ios_base and basic_ios functions, specifically imbue(), copyfmt(), and ~ios().

Definition at line 444 of file ios_base.h.

typedef _Ios_Fmtflags std::ios_base::fmtflags

This is a bitmask type. _Ios_Fmtflags is implementation-defined, but it is valid to perform bitwise operations on these values and expect the Right Thing to happen. Defined objects of type fmtflags are:

•
boolalpha
•
dec
•
fixed
•
hex
•
internal
•
left
•
oct
•
right
•
scientific
•
showbase
•
showpoint
•
showpos
•
skipws
•
unitbuf
•
uppercase
•
adjustfield
•
basefield
•
floatfield

Definition at line 263 of file ios_base.h.

typedef _Ios_Iostate std::ios_base::iostate

This is a bitmask type. _Ios_Iostate is implementation-defined, but it is valid to perform bitwise operations on these values and expect the Right Thing to happen. Defined objects of type iostate are:

•
badbit
•
eofbit
•
failbit
•
goodbit

Definition at line 338 of file ios_base.h.

typedef _Ios_Openmode std::ios_base::openmode

This is a bitmask type. _Ios_Openmode is implementation-defined, but it is valid to perform bitwise operations on these values and expect the Right Thing to happen. Defined objects of type openmode are:

•
app
•
ate
•
binary
•
in
•
out
•
trunc

Definition at line 369 of file ios_base.h.

typedef _Ios_Seekdir std::ios_base::seekdir

This is an enumerated type. _Ios_Seekdir is implementation-defined. Defined values of type seekdir are:

•
beg
•
cur, equivalent to SEEK_CUR in the C standard library.
•
end, equivalent to SEEK_END in the C standard library.

Definition at line 401 of file ios_base.h.

Member Enumeration Documentation

enum std::ios_base::event

The set of events that may be passed to an event callback. erase_event is used during ~ios() and copyfmt(). imbue_event is used during imbue(). copyfmt_event is used during copyfmt().

Definition at line 427 of file ios_base.h.

Constructor & Destructor Documentation

virtual std::ios_base::~ios_base () [virtual]Invokes each callback with erase_event. Destroys local storage.

Note that the ios_base object for the standard streams never gets destroyed. As a result, any callbacks registered with the standard streams will not get invoked with erase_event (unless copyfmt is used).

Member Function Documentation

const locale& std::ios_base::_M_getloc () const [inline]

Locale access. Returns:

A reference to the current locale.

Like getloc above, but returns a reference instead of generating a copy.

Definition at line 705 of file ios_base.h.

Referenced by std::money_get< _CharT, _InIter >::do_get(), std::num_get< _CharT, _InIter >::do_get(), std::time_get< _CharT, _InIter >::do_get_date(), std::time_get< _CharT, _InIter >::do_get_monthname(), std::time_get< _CharT, _InIter >::do_get_time(), std::time_get< _CharT, _InIter >::do_get_weekday(), std::time_get< _CharT, _InIter >::do_get_year(), std::time_put< _CharT, _OutIter >::do_put(), std::num_put< _CharT, _OutIter >::do_put(), and std::time_put< _CharT, _OutIter >::put().

fmtflags std::ios_base::flags () const [inline]

Access to format flags. Returns:

The format control flags for both input and output.

Definition at line 550 of file ios_base.h.

Referenced by std::basic_ios< _CharT, _Traits >::copyfmt(), std::num_get< _CharT, _InIter >::do_get(), std::num_put< _CharT, _OutIter >::do_put(), std::basic_ostream< _CharT, _Traits >::operator<<(), std::operator<<(), and std::operator>>().

fmtflags std::ios_base::flags (fmtflags __fmtfl) [inline]

Setting new format flags all at once. Parameters:

fmtfl The new flags to set.

Returns:

The previous format control flags.

This function overwrites all the format flags with fmtfl.

Definition at line 561 of file ios_base.h.

locale std::ios_base::getloc () const [inline]

Locale access. Returns:

A copy of the current locale.

If imbue(loc) has previously been called, then this function returns loc. Otherwise, it returns a copy of std::locale(), the global C++ locale.

Definition at line 694 of file ios_base.h.

Referenced by std::basic_ios< _CharT, _Traits >::copyfmt(), std::money_put< _CharT, _OutIter >::do_put(), std::basic_ios< _CharT, _Traits >::imbue(), std::operator>>(), and std::ws().

locale std::ios_base::imbue (const locale & __loc) throw ()

Setting a new locale. Parameters:

loc The new locale.

Returns:

The previous locale.

Sets the new locale for this stream, and then invokes each callback with imbue_event.

Reimplemented in std::basic_ios< _CharT, _Traits >, and std::basic_ios< char, _Traits >.

long& std::ios_base::iword (int __ix) [inline]

Access to integer array. Parameters:

__ix Index into the array.

Returns:

A reference to an integer associated with the index.

The iword function provides access to an array of integers that can be used for any purpose. The array grows as required to hold the supplied index. All integers in the array are initialized to 0.

The implementation reserves several indices. You should use xalloc to obtain an index that is safe to use. Also note that since the array can grow dynamically, it is not safe to hold onto the reference.

Definition at line 740 of file ios_base.h.

streamsize std::ios_base::precision () const [inline]

Flags access. Returns:

The precision to generate on certain output operations.

Be careful if you try to give a definition of precision here; see DR 189.

Definition at line 620 of file ios_base.h.

Referenced by std::basic_ios< _CharT, _Traits >::copyfmt(), and std::operator<<().

streamsize std::ios_base::precision (streamsize __prec) [inline]

Changing flags. Parameters:

prec The new precision value.

Returns:

The previous value of precision().

Definition at line 629 of file ios_base.h.

void*& std::ios_base::pword (int __ix) [inline]

Access to void pointer array. Parameters:

__ix Index into the array.

Returns:

A reference to a void* associated with the index.

The pword function provides access to an array of pointers that can be used for any purpose. The array grows as required to hold the supplied index. All pointers in the array are initialized to 0.

The implementation reserves several indices. You should use xalloc to obtain an index that is safe to use. Also note that since the array can grow dynamically, it is not safe to hold onto the reference.

Definition at line 761 of file ios_base.h.

void std::ios_base::register_callback (event_callback __fn, int __index)

Add the callback __fn with parameter __index. Parameters:

__fn The function to add.
__index The integer to pass to the function when invoked.

Registers a function as an event callback with an integer parameter to be passed to the function when invoked. Multiple copies of the function are allowed. If there are multiple callbacks, they are invoked in the order they were registered.

fmtflags std::ios_base::setf (fmtflags __fmtfl, fmtflags __mask) [inline]

Setting new format flags. Parameters:

fmtfl Additional flags to set.
mask The flags mask for fmtfl.

Returns:

The previous format control flags.

This function clears mask in the format flags, then sets fmtfl & mask. An example mask is ios_base::adjustfield.

Definition at line 594 of file ios_base.h.

fmtflags std::ios_base::setf (fmtflags __fmtfl) [inline]

Setting new format flags. Parameters:

fmtfl Additional flags to set.

Returns:

The previous format control flags.

This function sets additional flags in format control. Flags that were previously set remain set.

Definition at line 577 of file ios_base.h.

Referenced by std::boolalpha(), std::dec(), std::fixed(), std::hex(), std::internal(), std::left(), std::oct(), std::right(), std::scientific(), std::showbase(), std::showpoint(), std::showpos(), std::skipws(), std::unitbuf(), and std::uppercase().

static bool std::ios_base::sync_with_stdio (bool __sync = true) [static]

Interaction with the standard C I/O objects. Parameters:

sync Whether to synchronize or not.

Returns:

True if the standard streams were previously synchronized.

The synchronization referred to is only that between the standard C facilities (e.g., stdout) and the standard C++ objects (e.g., cout). User-declared streams are unaffected. See http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt11ch28s02.html

void std::ios_base::unsetf (fmtflags __mask) [inline]

Clearing format flags. Parameters:

mask The flags to unset.

This function clears mask in the format flags.

Definition at line 609 of file ios_base.h.

Referenced by std::noboolalpha(), std::noshowbase(), std::noshowpoint(), std::noshowpos(), std::noskipws(), std::nounitbuf(), and std::nouppercase().

streamsize std::ios_base::width () const [inline]

Flags access. Returns:

The minimum field width to generate on output operations.

Minimum field width refers to the number of characters.

Definition at line 643 of file ios_base.h.

Referenced by std::basic_ios< _CharT, _Traits >::copyfmt(), std::num_put< _CharT, _OutIter >::do_put(), and std::operator>>().

streamsize std::ios_base::width (streamsize __wide) [inline]

Changing flags. Parameters:

wide The new width value.

Returns:

The previous value of width().

Definition at line 652 of file ios_base.h.

static int std::ios_base::xalloc () throw () [static]

Access to unique indices. Returns:

An integer different from all previous calls.

This function returns a unique integer every time it is called. It can be used for any purpose, but is primarily intended to be a unique index for the iword and pword functions. The expectation is that an application calls xalloc in order to obtain an index in the iword and pword arrays that can be used without fear of conflict.

The implementation maintains a static variable that is incremented and returned on each invocation. xalloc is guaranteed to return an index that is safe to use in the iword and pword arrays.

Member Data Documentation

const fmtflags std::ios_base::adjustfield [static]

A mask of left|right|internal. Useful for the 2-arg form of setf.

Definition at line 318 of file ios_base.h.

Referenced by std::num_put< _CharT, _OutIter >::do_put().

const openmode std::ios_base::app [static]

Seek to end before each write.

Definition at line 372 of file ios_base.h.

const openmode std::ios_base::ate [static]

Open and seek to end immediately after opening.

Definition at line 375 of file ios_base.h.

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

const iostate std::ios_base::badbit [static]

Indicates a loss of integrity in an input or output sequence (such /// as an irrecoverable read error from a file).

Definition at line 342 of file ios_base.h.

Referenced by std::basic_ostream< _CharT, _Traits >::flush(), std::basic_istream< _CharT, _Traits >::get(), std::basic_istream< _CharT, _Traits >::getline(), std::basic_istream< _CharT, _Traits >::ignore(), std::basic_ios< _CharT, _Traits >::init(), std::operator<<(), std::basic_ostream< _CharT, _Traits >::operator<<(), std::operator>>(), std::basic_istream< _CharT, _Traits >::operator>>(), std::basic_istream< _CharT, _Traits >::peek(), std::basic_ostream< _CharT, _Traits >::put(), std::basic_istream< _CharT, _Traits >::putback(), std::basic_istream< _CharT, _Traits >::read(), std::basic_istream< _CharT, _Traits >::readsome(), std::basic_istream< _CharT, _Traits >::seekg(), std::basic_ostream< _CharT, _Traits >::seekp(), std::basic_istream< _CharT, _Traits >::sync(), std::basic_istream< _CharT, _Traits >::tellg(), std::basic_ostream< _CharT, _Traits >::tellp(), and std::basic_istream< _CharT, _Traits >::unget().

const fmtflags std::ios_base::basefield [static]

A mask of dec|oct|hex. Useful for the 2-arg form of setf.

Definition at line 321 of file ios_base.h.

Referenced by std::num_get< _CharT, _InIter >::do_get(), and std::basic_ostream< _CharT, _Traits >::operator<<().

const seekdir std::ios_base::beg [static]

Request a seek relative to the beginning of the stream.

Definition at line 404 of file ios_base.h.

const openmode std::ios_base::binary [static]

Perform input and output in binary mode (as opposed to text mode). /// This is probably not what you think it is; see /// http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt11ch27s02.html.

Definition at line 380 of file ios_base.h.

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

const fmtflags std::ios_base::boolalpha [static]

Insert/extract bool in alphabetic rather than numeric format.

Definition at line 266 of file ios_base.h.

Referenced by std::num_get< _CharT, _InIter >::do_get(), and std::num_put< _CharT, _OutIter >::do_put().

const seekdir std::ios_base::cur [static]

Request a seek relative to the current position within the sequence.

Definition at line 407 of file ios_base.h.

Referenced by std::basic_filebuf< _CharT, _Traits >::imbue(), std::basic_istream< _CharT, _Traits >::tellg(), and std::basic_ostream< _CharT, _Traits >::tellp().

const fmtflags std::ios_base::dec [static]

Converts integer input or generates integer output in decimal base.

Definition at line 269 of file ios_base.h.

const seekdir std::ios_base::end [static]

Request a seek relative to the current end of the sequence.

Definition at line 410 of file ios_base.h.

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

const iostate std::ios_base::eofbit [static]

Indicates that an input operation reached the end of an input sequence.

Definition at line 345 of file ios_base.h.

Referenced by std::num_get< _CharT, _InIter >::do_get(), std::time_get< _CharT, _InIter >::do_get_date(), std::time_get< _CharT, _InIter >::do_get_monthname(), std::time_get< _CharT, _InIter >::do_get_time(), std::time_get< _CharT, _InIter >::do_get_weekday(), std::time_get< _CharT, _InIter >::do_get_year(), std::basic_istream< _CharT, _Traits >::get(), std::basic_istream< _CharT, _Traits >::getline(), std::basic_istream< _CharT, _Traits >::ignore(), std::operator>>(), std::basic_istream< _CharT, _Traits >::operator>>(), std::basic_istream< _CharT, _Traits >::peek(), std::basic_istream< _CharT, _Traits >::read(), std::basic_istream< _CharT, _Traits >::readsome(), and std::ws().

const iostate std::ios_base::failbit [static]

Indicates that an input operation failed to read the expected /// characters, or that an output operation failed to generate the /// desired characters.

Definition at line 350 of file ios_base.h.

Referenced by std::num_get< _CharT, _InIter >::do_get(), std::time_get< _CharT, _InIter >::do_get_monthname(), std::time_get< _CharT, _InIter >::do_get_weekday(), std::time_get< _CharT, _InIter >::do_get_year(), std::basic_istream< _CharT, _Traits >::get(), std::basic_istream< _CharT, _Traits >::getline(), std::basic_ostream< _CharT, _Traits >::operator<<(), std::basic_istream< _CharT, _Traits >::operator>>(), std::operator>>(), std::basic_istream< _CharT, _Traits >::read(), std::basic_istream< _CharT, _Traits >::seekg(), and std::basic_ostream< _CharT, _Traits >::seekp().

const fmtflags std::ios_base::fixed [static]

Generate floating-point output in fixed-point notation.

Definition at line 272 of file ios_base.h.

const fmtflags std::ios_base::floatfield [static]

A mask of scientific|fixed. Useful for the 2-arg form of setf.

Definition at line 324 of file ios_base.h.

const iostate std::ios_base::goodbit [static]

Indicates all is well.

Definition at line 353 of file ios_base.h.

Referenced by std::num_get< _CharT, _InIter >::do_get(), std::time_get< _CharT, _InIter >::do_get_monthname(), std::time_get< _CharT, _InIter >::do_get_weekday(), std::time_get< _CharT, _InIter >::do_get_year(), std::basic_ostream< _CharT, _Traits >::flush(), std::basic_istream< _CharT, _Traits >::get(), std::basic_istream< _CharT, _Traits >::getline(), std::basic_istream< _CharT, _Traits >::ignore(), std::basic_ios< _CharT, _Traits >::init(), std::basic_ostream< _CharT, _Traits >::operator<<(), std::operator>>(), std::basic_istream< _CharT, _Traits >::operator>>(), std::basic_istream< _CharT, _Traits >::peek(), std::basic_ostream< _CharT, _Traits >::put(), std::basic_istream< _CharT, _Traits >::putback(), std::basic_istream< _CharT, _Traits >::read(), std::basic_istream< _CharT, _Traits >::readsome(), std::basic_istream< _CharT, _Traits >::seekg(), std::basic_ostream< _CharT, _Traits >::seekp(), std::basic_istream< _CharT, _Traits >::sync(), and std::basic_istream< _CharT, _Traits >::unget().

const fmtflags std::ios_base::hex [static]

Converts integer input or generates integer output in hexadecimal base.

Definition at line 275 of file ios_base.h.

Referenced by std::num_get< _CharT, _InIter >::do_get(), std::num_put< _CharT, _OutIter >::do_put(), and std::basic_ostream< _CharT, _Traits >::operator<<().

const openmode std::ios_base::in [static]

Open for input. Default for ifstream and fstream.

Definition at line 383 of file ios_base.h.

Referenced by std::basic_istream< _CharT, _Traits >::seekg(), std::basic_filebuf< _CharT, _Traits >::showmanyc(), std::basic_istream< _CharT, _Traits >::tellg(), std::basic_stringbuf< _CharT, _Traits, _Alloc >::underflow(), and std::basic_filebuf< _CharT, _Traits >::underflow().

const fmtflags std::ios_base::internal [static]

Adds fill characters at a designated internal point in certain /// generated output, or identical to right if no such point is /// designated.

Definition at line 280 of file ios_base.h.

const fmtflags std::ios_base::left [static]

Adds fill characters on the right (final positions) of certain /// generated output. (I.e., the thing you print is flush left.).

Definition at line 284 of file ios_base.h.

Referenced by std::num_put< _CharT, _OutIter >::do_put().

const fmtflags std::ios_base::oct [static]

Converts integer input or generates integer output in octal base.

Definition at line 287 of file ios_base.h.

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

const openmode std::ios_base::out [static]

Open for output. Default for ofstream and fstream.

Definition at line 386 of file ios_base.h.

Referenced by std::basic_ostream< _CharT, _Traits >::seekp(), and std::basic_ostream< _CharT, _Traits >::tellp().

const fmtflags std::ios_base::right [static]

Adds fill characters on the left (initial positions) of certain /// generated output. (I.e., the thing you print is flush right.).

Definition at line 291 of file ios_base.h.

const fmtflags std::ios_base::scientific [static]

Generates floating-point output in scientific notation.

Definition at line 294 of file ios_base.h.

const fmtflags std::ios_base::showbase [static]

Generates a prefix indicating the numeric base of generated integer /// output.

Definition at line 298 of file ios_base.h.

const fmtflags std::ios_base::showpoint [static]

Generates a decimal-point character unconditionally in generated /// floating-point output.

Definition at line 302 of file ios_base.h.

const fmtflags std::ios_base::showpos [static]

Generates a + sign in non-negative generated numeric output.

Definition at line 305 of file ios_base.h.

const fmtflags std::ios_base::skipws [static]

Skips leading white space before certain input operations.

Definition at line 308 of file ios_base.h.

const openmode std::ios_base::trunc [static]

Open for input. Default for ofstream.

Definition at line 389 of file ios_base.h.

const fmtflags std::ios_base::unitbuf [static]

Flushes output after each output operation.

Definition at line 311 of file ios_base.h.

const fmtflags std::ios_base::uppercase [static]

Replaces certain lowercase letters with their uppercase equivalents /// in generated output.

Definition at line 315 of file ios_base.h.

Referenced by std::num_put< _CharT, _OutIter >::do_put().

Author

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