ios_base Class

Article
07/29/2015

The class describes the storage and member functions common to both input and output streams that do not depend on the template parameters. (The template class basic_ios describes what is common and is dependent on template parameters.)

An object of class ios_base stores formatting information, which consists of:

Format flags in an object of type fmtflags.
An exception mask in an object of type iostate.
A field width in an object of type int*.*
A display precision in an object of type int.
A locale object in an object of type locale.
Two extensible arrays, with elements of type long and void pointer.

An object of class ios_base also stores stream state information, in an object of type iostate, and a callback stack.

Constructors

ios_base

Constructs ios_base objects.

Typedefs

event_callback	Describes a function passed to register_call.
fmtflags	Constants to specify the appearance of output.
iostate	Defines constants describing the state of a stream.
openmode	Describes how to interact with a stream.
seekdir	Specifies starting point for offset operations.

Enums

event

Specifies event types.

Constants

adjustfield	A bitmask defined as internal \| left \| right.
app	Specifies seeking to the end of a stream before each insertion.
ate	Specifies seeking to the end of a stream when its controlling object is first created.
badbit	Records a loss of integrity of the stream buffer.
basefield	A bitmask defined as dec \| hex \| oct.
beg	Specifies seeking relative to the beginning of a sequence.
binary	Specifies that a file should be read as a binary stream, rather than as a text stream.
boolalpha	Specifies insertion or extraction of objects of type bool as names (such as true and false) rather than as numeric values.
cur	Specifies seeking relative to the current position within a sequence.
dec	Specifies insertion or extraction of integer values in decimal format.
end	Specifies seeking relative to the end of a sequence.
eofbit	Records end-of-file while extracting from a stream.
failbit	Records a failure to extract a valid field from a stream.
fixed	Specifies insertion of floating-point values in fixed-point format (with no exponent field).
floatfield	A bitmask defined as fixed \| scientific
goodbit	All state bits clear.
hex	Specifies insertion or extraction of integer values in hexadecimal format.
in	Specifies extraction from a stream.
internal	Pads to a field width by inserting fill characters at a point internal to a generated numeric field.
left	Specifies left justification.
oct	Specifies insertion or extraction of integer values in octal format.
out	Specifies insertion to a stream.
right	Specifies right justification.
scientific	Specifies insertion of floating-point values in scientific format (with an exponent field).
showbase	Specifies insertion of a prefix that reveals the base of a generated integer field.
showpoint	Specifies unconditional insertion of a decimal point in a generated floating-point field.
showpos	Specifies insertion of a plus sign in a nonnegative generated numeric field.
skipws	Specifies skipping leading white space before certain extractions.
trunc	Specifies deleting contents of an existing file when its controlling object is created.
unitbuf	Causes output to be flushed after each insertion.
uppercase	Specifies insertion of uppercase equivalents of lowercase letters in certain insertions.

Member Functions

failure	The member class serves as the base class for all exceptions thrown by the member function clear in template class basic_ios.
flags	Sets or returns the current flag settings.
getloc	Returns the stored locale object.
imbue	Changes the locale.
Init	Creates the standard iostream objects when constructed.
iword	Assigns a value to be stored as an iword.
precision	Specifies the number of digits to display in a floating-point number.
pword	Assigns a value to be stored as a pword.
register_callback	Specifies a callback function.
setf	Sets the specified flags.
sync_with_stdio	Ensures that iostream and C run-time library operations occur in the order that they appear in source code.
unsetf	Causes the specified flags to be off.
width	Sets the length of the output stream.
xalloc	Specifies that a variable shall be part of the stream.

Operators

operator=

The assignment operator for ios_base objects.

Requirements

Header: <ios>

Namespace: std

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