class
<ios> <iostream>

std::ios_base

class ios_base;
Base class for streams

Base class for the entire hierarchy of stream classes in the standard input/output library, describing the most basic part of a stream which is common to all stream objects, independently of their character type.

It has no public constructors, and thus no objects of this class can be declared.

Both ios_base and its derived class basic_ios define the components of streams that do not depend on whether the stream is an input or an output stream: ios_base describes the members that are independent of the template parameters (i.e. the character type and traits), while basic_ios describes the members that do depend on them.

More specifically, the ios_base class maintains the following information of a stream:

fieldmember functionsdescription
Formattingformat flagsflags
setf
unsetf		A set of internal flags that affect how certain input/output operations are interpreted or generated.
See member type fmtflags.
field widthwidthWidth of the next formatted element to insert.
display precisionprecisionDecimal precision for the next floating-point value inserted.
localegetloc
imbue		The locale object used by the function for formatted input/output operations affected by localization properties.
Othercallback stackregister_callbackStack of pointers to functions that are called when certain events occur.
extensible arraysiword
pword
xalloc		Internal arrays to store objects of type long and void*.

Member Functions

(constructor)
Construct object (public member function )
(destructor)
Destruct object (public member function )

Formatting:
flags
Get/set format flags (public member function )
setf
Set specific format flags (public member function )
unsetf
Clear specific format flags (public member function )
precision
Get/Set floating-point decimal precision (public member function )
width
Get/set field width (public member function )

Locales:
imbue
Imbue locale (public member function )
getloc
Get current locale (public member function )

Internal extensible array:
xalloc
Get new index for extensible array [static] (public static member function )
iword
Get integer element of extensible array (public member function )
pword
Get pointer element of extensible array (public member function )

Others:
register_callback
Register event callback function (public member function )
sync_with_stdio
Toggle synchronization with cstdio streams [static] (public static member function )

Member types

event
Type to indicate event type (public member type )
event_callback
Event callback function type (public member type )
fmtflags
Type for stream format flags (public member type )
iostate
Type for stream state flags (public member type )
openmode
Type for stream opening mode flags (public member type )
seekdir
Type for stream seeking direction flag (public member type )

Member classes

failure
Base class for stream exceptions (public member class )
Init
Initialize standard stream objects (public member class )

Member constants

Streams have member constants with the possible values for member types fmtflags, iostate, openmode and seekdir (see the description of each type for more info).

C++