libstdc++
std::ios_base Class Reference
Inheritance diagram for std::ios_base:
Inheritance graph

Classes

class  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

const locale_M_getloc () const
 
fmtflags flags () const
 
fmtflags flags (fmtflags __fmtfl)
 
locale getloc () const
 
locale imbue (const locale &__loc)
 
long & iword (int __ix)
 
streamsize precision () const
 
streamsize precision (streamsize __prec)
 
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)
 
virtual ~ios_base ()
 

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)
 
_Words & _M_grow_words (int __index, bool __iword)
 
void _M_init ()
 

Protected Attributes

_Callback_list * _M_callbacks
 
locale _M_ios_locale
 
_Words _M_local_word [_S_local_word_size]
 
_Words * _M_word
 
int _M_word_size
 
_Words _M_word_zero
 
streamsize _M_precision
 
streamsize _M_width
 
fmtflags _M_flags
 
iostate _M_exception
 
iostate _M_streambuf_state
 

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
eventOne of the members of the event enum.
ios_baseReference to the ios_base object.
intThe 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

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

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

Access to format flags.

Returns
The format control flags for both input and output.

Definition at line 555 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(), and std::operator<<().

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

Setting new format flags all at once.

Parameters
fmtflThe new flags to set.
Returns
The previous format control flags.

This function overwrites all the format flags with fmtfl.

Definition at line 566 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 699 of file ios_base.h.

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

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

Setting a new locale.

Parameters
locThe new locale.
Returns
The previous locale.

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

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

Access to integer array.

Parameters
__ixIndex 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 745 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 625 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
precThe new precision value.
Returns
The previous value of precision().

Definition at line 634 of file ios_base.h.

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

Access to void pointer array.

Parameters
__ixIndex 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 766 of file ios_base.h.

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

Add the callback __fn with parameter __index.

Parameters
__fnThe function to add.
__indexThe 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)
inline

Setting new format flags.

Parameters
fmtflAdditional 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 582 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().

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

Setting new format flags.

Parameters
fmtflAdditional flags to set.
maskThe 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 599 of file ios_base.h.

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

Interaction with the standard C I/O objects.

Parameters
syncWhether 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
maskThe flags to unset.

This function clears mask in the format flags.

Definition at line 614 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 648 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
wideThe new width value.
Returns
The previous value of width().

Definition at line 657 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

iostate std::ios_base::_M_exception
protected

ios_base data members (doc me)

Definition at line 467 of file ios_base.h.

fmtflags std::ios_base::_M_flags
protected

ios_base data members (doc me)

Definition at line 466 of file ios_base.h.

streamsize std::ios_base::_M_precision
protected

ios_base data members (doc me)

Definition at line 464 of file ios_base.h.

iostate std::ios_base::_M_streambuf_state
protected

ios_base data members (doc me)

Definition at line 468 of file ios_base.h.

streamsize std::ios_base::_M_width
protected

ios_base data members (doc me)

Definition at line 465 of file ios_base.h.

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.

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.

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.

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.

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

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.

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_filebuf< _CharT, _Traits >::pbackfail(), and std::basic_filebuf< _CharT, _Traits >::seekoff().

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.

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.

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.

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.

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.

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.

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_filebuf< _CharT, _Traits >::overflow(), and std::basic_filebuf< _CharT, _Traits >::xsputn().

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.


The documentation for this class was generated from the following file: