C++ Library - <ios_base>

---

Introduction

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 −

	field	member functions	description
Formatting	format flags	flags setf unsetf	A set of internal flags that affect how certain input/output operations are interpreted or generated. See member type fmtflags.
	field width	width	Width of the next formatted element to insert.
	display precision	precision	Decimal precision for the next floating-point value inserted.
	locale	getloc imbue	The locale object used by the function for formatted input/output operations affected by localization properties.
Other	callback stack	register_callback	Stack of pointers to functions that are called when certain events occur.
	extensible arrays	iword pword xalloc	Internal arrays to store objects of type long and void*.

Definition

Below is definition of ios_base as shown below −

class ios_base;

Member types

Sr.No.	Member types	Definition
1	event	Type to indicate event type
2	event_callback	Event callback function type
3	fmtflags	Type for stream format flags
4	iostate	Type for stream state flags
5	openmode	Type for stream opening mode flags
6	seekdir	Type for stream seeking direction flag

Public Member Functions

Sr.No.	Member types	Definition
1	(constructor)	Construct object (public member function )
2	(destructor)	Destruct object (public member function )

Formatting

Sr.No.	Member types	Definition
1	flags	It is used to get/set format flags
2	setf	It is used to set specific format flags
3	unsetf	It is used to clear specific format flags
4	precision	It is used to get/Set floating-point decimal precision
5	width	It is used to get/set field width

Locales

Sr.No.	Member types	Definition
1	imbue	Imbue locale
2	getloc	Get current locale

Internal extensible array

Sr.No.	Member types	Definition
1	xalloc	It is used to get new index for extensible array [static]
2	iword	It is used to get integer element of extensible array
3	pword	It is used to get pointer element of extensible array

Others

Sr.No.	Member types	Definition
1	register_callback	Register event callback function
2	sync_with_stdio	Toggle synchronization with cstdio streams [static]