<ios> <iostream>


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
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.
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
Internal arrays to store objects of type long and void*.

Member Functions



Internal extensible array:


Member types

Member classes

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).