Provided by: libstdc++6-4.7-doc_4.7.4-3ubuntu12_all 
NAME
std::ios_base -
SYNOPSIS
Inherited by std::basic_ios< _CharT, _Traits >.
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 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 () 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 ()
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 201 of file ios_base.h.
Member Typedef Documentation
typedef void(* std::ios_base::event_callback) (event __e, ios_base &__b, int __i)
The type of an event callback function.
Parameters:
__e One of the members of the event enum.
__b Reference to the ios_base object.
__i 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 438 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 257 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 332 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 363 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 395 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 421 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 708 of file ios_base.h.
fmtflags std::ios_base::flags () const [inline]
Access to format flags.
Returns:
The format control flags for both input and output.
Definition at line 553 of file ios_base.h.
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 564 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 697 of file ios_base.h.
locale std::ios_base::imbue (const locale & __loc)
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.
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 743 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 623 of file ios_base.h.
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 632 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 764 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) [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 580 of file ios_base.h.
Referenced by std::boolalpha(), std::dec(), std::fixed(), std::hex(), 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:
__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 597 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:
__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 612 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 646 of file ios_base.h.
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 655 of file ios_base.h.
static int std::ios_base::xalloc () [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 312 of file ios_base.h.
Referenced by std::internal(), std::left(), and std::right().
const openmode std::ios_base::app [static]
Seek to end before each write.
Definition at line 366 of file ios_base.h.
const openmode std::ios_base::ate [static]
Open and seek to end immediately after opening.
Definition at line 369 of file ios_base.h.
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 336 of file ios_base.h.
Referenced by std::basic_ios< _CharT, _Traits >::bad(), and std::basic_ios< _CharT, _Traits >::fail().
const fmtflags std::ios_base::basefield [static]
A mask of dec|oct|hex. Useful for the 2-arg form of setf.
Definition at line 315 of file ios_base.h.
Referenced by std::dec(), std::hex(), and std::oct().
const seekdir std::ios_base::beg [static]
Request a seek relative to the beginning of the stream.
Definition at line 398 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 374 of file ios_base.h.
const fmtflags std::ios_base::boolalpha [static]
Insert/extract bool in alphabetic rather than numeric format.
Definition at line 260 of file ios_base.h.
Referenced by std::boolalpha(), and std::noboolalpha().
const seekdir std::ios_base::cur [static]
Request a seek relative to the current position within the sequence.
Definition at line 401 of file ios_base.h.
const fmtflags std::ios_base::dec [static]
Converts integer input or generates integer output in decimal base.
Definition at line 263 of file ios_base.h.
Referenced by std::dec().
const seekdir std::ios_base::end [static]
Request a seek relative to the current end of the sequence.
Definition at line 404 of file ios_base.h.
const iostate std::ios_base::eofbit [static]
Indicates that an input operation reached the end of an input sequence.
Definition at line 339 of file ios_base.h.
Referenced by std::basic_ios< _CharT, _Traits >::eof().
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 344 of file ios_base.h.
Referenced by std::basic_ios< _CharT, _Traits >::fail().
const fmtflags std::ios_base::fixed [static]
Generate floating-point output in fixed-point notation.
Definition at line 266 of file ios_base.h.
Referenced by std::fixed().
const fmtflags std::ios_base::floatfield [static]
A mask of scientific|fixed. Useful for the 2-arg form of setf.
Definition at line 318 of file ios_base.h.
Referenced by std::fixed(), and std::scientific().
const iostate std::ios_base::goodbit [static]
Indicates all is well.
Definition at line 347 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 269 of file ios_base.h.
Referenced by std::hex().
const openmode std::ios_base::in [static]
Open for input. Default for ifstream and fstream.
Definition at line 377 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 274 of file ios_base.h.
Referenced by std::internal().
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 278 of file ios_base.h.
Referenced by std::left().
const fmtflags std::ios_base::oct [static]
Converts integer input or generates integer output in octal base.
Definition at line 281 of file ios_base.h.
Referenced by std::oct().
const openmode std::ios_base::out [static]
Open for output. Default for ofstream and fstream.
Definition at line 380 of file ios_base.h.
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 285 of file ios_base.h.
Referenced by std::right().
const fmtflags std::ios_base::scientific [static]
Generates floating-point output in scientific notation.
Definition at line 288 of file ios_base.h.
Referenced by std::scientific().
const fmtflags std::ios_base::showbase [static]
Generates a prefix indicating the numeric base of generated integer output.
Definition at line 292 of file ios_base.h.
Referenced by std::noshowbase(), and std::showbase().
const fmtflags std::ios_base::showpoint [static]
Generates a decimal-point character unconditionally in generated floating-point output.
Definition at line 296 of file ios_base.h.
Referenced by std::noshowpoint(), and std::showpoint().
const fmtflags std::ios_base::showpos [static]
Generates a + sign in non-negative generated numeric output.
Definition at line 299 of file ios_base.h.
Referenced by std::noshowpos(), and std::showpos().
const fmtflags std::ios_base::skipws [static]
Skips leading white space before certain input operations.
Definition at line 302 of file ios_base.h.
Referenced by std::noskipws(), and std::skipws().
const openmode std::ios_base::trunc [static]
Open for input. Default for ofstream.
Definition at line 383 of file ios_base.h.
const fmtflags std::ios_base::unitbuf [static]
Flushes output after each output operation.
Definition at line 305 of file ios_base.h.
Referenced by std::nounitbuf(), and std::unitbuf().
const fmtflags std::ios_base::uppercase [static]
Replaces certain lowercase letters with their uppercase equivalents in generated output.
Definition at line 309 of file ios_base.h.
Referenced by std::nouppercase(), and std::uppercase().
Author
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libstdc++ Mon Jan 18 2016 std::ios_base(3cxx)