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

class  failure
 

Public Types

enum  event { erase_event , imbue_event , copyfmt_event }
 
typedef void(* event_callback) (event __e, ios_base &__b, int __i)
 
typedef _Ios_Fmtflags fmtflags
 
typedef _Ios_Iostate iostate
 
typedef _Ios_Openmode openmode
 
typedef _Ios_Seekdir seekdir
 

Public Member Functions

 ios_base (const ios_base &)=delete
 
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)
 
ios_baseoperator= (const ios_base &)=delete
 
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)
 

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 ()
 
void _M_move (ios_base &) noexcept
 
void _M_swap (ios_base &__rhs) noexcept
 

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 228 of file ios_base.h.

Member Typedef Documentation

◆ event_callback

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

The type of an event callback function.

Parameters
__eOne of the members of the event enum.
__bReference to the ios_base object.
__iThe 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 529 of file ios_base.h.

◆ fmtflags

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 341 of file ios_base.h.

◆ iostate

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 416 of file ios_base.h.

◆ openmode

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 447 of file ios_base.h.

◆ seekdir

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 479 of file ios_base.h.

Member Enumeration Documentation

◆ 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 512 of file ios_base.h.

Constructor & Destructor Documentation

◆ ~ios_base()

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

◆ _M_getloc()

◆ flags() [1/2]

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

◆ flags() [2/2]

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 660 of file ios_base.h.

◆ getloc()

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 793 of file ios_base.h.

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

◆ imbue()

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

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.

Referenced by std::basic_ios< _CharT, _Traits >::imbue().

◆ iword()

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 839 of file ios_base.h.

◆ precision() [1/2]

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 719 of file ios_base.h.

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

◆ precision() [2/2]

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

Changing flags.

Parameters
__precThe new precision value.
Returns
The previous value of precision().

Definition at line 728 of file ios_base.h.

◆ pword()

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 860 of file ios_base.h.

◆ register_callback()

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.

◆ setf() [1/2]

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 676 of file ios_base.h.

Referenced by std::__detail::operator>>().

◆ setf() [2/2]

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 693 of file ios_base.h.

◆ sync_with_stdio()

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 https://gcc.gnu.org/onlinedocs/libstdc++/manual/fstreams.html#std.io.filestreams.binary

◆ unsetf()

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 708 of file ios_base.h.

◆ width() [1/2]

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 742 of file ios_base.h.

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

◆ width() [2/2]

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

Changing flags.

Parameters
__wideThe new width value.
Returns
The previous value of width().

Definition at line 751 of file ios_base.h.

◆ xalloc()

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

◆ adjustfield

const fmtflags std::ios_base::adjustfield
static

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

Definition at line 396 of file ios_base.h.

Referenced by std::num_put< _CharT, _OutIter >::do_put(), std::internal(), std::left(), and std::right().

◆ app

const openmode std::ios_base::app
static

◆ ate

const openmode std::ios_base::ate
static

Open and seek to end immediately after opening.

Definition at line 453 of file ios_base.h.

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

◆ badbit

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 420 of file ios_base.h.

Referenced by std::basic_ostream< _CharT, _Traits >::sentry::~sentry(), std::basic_ios< _CharT, _Traits >::bad(), std::basic_ios< _CharT, _Traits >::fail(), std::basic_istream< char >::get(), and std::basic_istream< char >::ignore().

◆ basefield

const fmtflags std::ios_base::basefield
static

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

Definition at line 399 of file ios_base.h.

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

◆ beg

const seekdir std::ios_base::beg
static

Request a seek relative to the beginning of the stream.

Definition at line 482 of file ios_base.h.

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

◆ binary

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 https://gcc.gnu.org/onlinedocs/libstdc++/manual/fstreams.html#std.io.filestreams.binary.

Definition at line 458 of file ios_base.h.

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

◆ boolalpha

const fmtflags std::ios_base::boolalpha
static

Insert/extract bool in alphabetic rather than numeric format.

Definition at line 344 of file ios_base.h.

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

◆ cur

◆ dec

const fmtflags std::ios_base::dec
static

Converts integer input or generates integer output in decimal base.

Definition at line 347 of file ios_base.h.

Referenced by std::dec().

◆ end

const seekdir std::ios_base::end
static

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

Definition at line 488 of file ios_base.h.

Referenced by std::basic_filebuf< _CharT, _Traits >::open(), and std::basic_stringbuf< _CharT, _Traits, _Alloc >::seekoff().

◆ eofbit

◆ failbit

◆ fixed

const fmtflags std::ios_base::fixed
static

Generate floating-point output in fixed-point notation.

Definition at line 350 of file ios_base.h.

Referenced by std::fixed(), and std::hexfloat().

◆ floatfield

const fmtflags std::ios_base::floatfield
static

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

Definition at line 402 of file ios_base.h.

Referenced by std::defaultfloat(), std::fixed(), std::hexfloat(), and std::scientific().

◆ goodbit

◆ hex

const fmtflags std::ios_base::hex
static

Converts integer input or generates integer output in hexadecimal base.

Definition at line 353 of file ios_base.h.

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

◆ in

◆ internal

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 358 of file ios_base.h.

Referenced by std::internal().

◆ left

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 362 of file ios_base.h.

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

◆ oct

const fmtflags std::ios_base::oct
static

Converts integer input or generates integer output in octal base.

Definition at line 365 of file ios_base.h.

Referenced by std::oct().

◆ out

◆ right

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 369 of file ios_base.h.

Referenced by std::right().

◆ scientific

const fmtflags std::ios_base::scientific
static

Generates floating-point output in scientific notation.

Definition at line 372 of file ios_base.h.

Referenced by std::hexfloat(), and std::scientific().

◆ showbase

const fmtflags std::ios_base::showbase
static

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

Definition at line 376 of file ios_base.h.

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

◆ showpoint

const fmtflags std::ios_base::showpoint
static

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

Definition at line 380 of file ios_base.h.

Referenced by std::noshowpoint(), and std::showpoint().

◆ showpos

const fmtflags std::ios_base::showpos
static

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

Definition at line 383 of file ios_base.h.

Referenced by std::noshowpos(), and std::showpos().

◆ skipws

const fmtflags std::ios_base::skipws
static

Skips leading white space before certain input operations.

Definition at line 386 of file ios_base.h.

Referenced by std::noskipws(), std::__detail::operator>>(), and std::skipws().

◆ trunc

const openmode std::ios_base::trunc
static

Truncate an existing stream when opening. Default for ofstream.

Definition at line 467 of file ios_base.h.

◆ unitbuf

const fmtflags std::ios_base::unitbuf
static

Flushes output after each output operation.

Definition at line 389 of file ios_base.h.

Referenced by std::basic_ostream< _CharT, _Traits >::sentry::~sentry(), std::nounitbuf(), and std::unitbuf().

◆ uppercase

const fmtflags std::ios_base::uppercase
static

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

Definition at line 393 of file ios_base.h.

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


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