Defined in header <ios> | ||
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class ios_base; |
The class ios_base
is a multipurpose class that serves as the base class for all I/O stream classes. It maintains several kinds of data:
1) state information: stream status flags
2) control information: flags that control formatting of both input and output sequences and the imbued locale
3) private storage: indexed extensible data structure that allows both
long
and void*
members, which may be implemented as two arbitrary-length arrays or a single array of two-element structs or another container. 4) callbacks: arbitrary number of user-defined functions to be called from imbue(), copyfmt(), and ~ios_base()
Typical implementation holds member constants corresponding to all values of fmtflags, iostate, openmode, and seekdir shown below, member variables to maintain current precision, width, and formatting flags, the exception mask, the buffer error state, a resizeable container holding the callbacks, the currently imbued locale, the private storage, and a static integer variable for xalloc().
Member functions
constructs the object (protected member function) | |
(destructor)
[virtual] | destructs the object (virtual public member function) |
Formatting | |
manages format flags (public member function) | |
sets specific format flag (public member function) | |
clears specific format flag (public member function) | |
manages decimal precision of floating point operations (public member function) | |
manages field width (public member function) | |
Locales | |
sets locale (public member function) | |
returns current locale (public member function) | |
Internal extensible array | |
[static] | returns a program-wide unique integer that is safe to use as index to pword() and iword() (public static member function) |
resizes the private storage if necessary and access to the long element at the given index (public member function) | |
resizes the private storage if necessary and access to the void* element at the given index (public member function) | |
Miscellaneous | |
registers event callback function (public member function) | |
[static] | sets whether C++ and C IO libraries are interoperable (public static member function) |
Member classes | |
stream exception (public member class) | |
initializes standard stream objects (public member class) |
Member types and constants | |||||||||||||||||||||||||||||||||||||||
Type | Explanation | ||||||||||||||||||||||||||||||||||||||
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stream open mode type The following constants are also defined:
(typedef) | |||||||||||||||||||||||||||||||||||||||
formatting flags type The following constants are also defined:
(typedef) | |||||||||||||||||||||||||||||||||||||||
state of the stream type The following constants are also defined:
(typedef) | |||||||||||||||||||||||||||||||||||||||
seeking direction type The following constants are also defined:
(typedef) | |||||||||||||||||||||||||||||||||||||||
specifies event type (enum) | |||||||||||||||||||||||||||||||||||||||
callback function type (typedef) |
| (until C++17) |
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