class

std::basic_ostream

template <class charT, class traits = char_traits<charT> >  class basic_ostream;

Output stream

ios_base
basic_ios
basic_ostream
basic_iostreambasic_ofstreambasic_ostringstream

Output stream objects can write sequences of characters and represent other kinds of data. Specific members are provided to perform these output operations (see functions below).

The standard objects cout, cerr, clog, wcout, wcerr and wclog use particular instantiations of this class template.

Objects of these classes keep a set of internal fields inherited from ios_base and basic_ios:

	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.
	fill character	`fill`	Character to pad a formatted field up to the field width (`width`).
State	error state	`rdstate` `setstate` `clear`	The current error state of the stream. Individual values may be obtained by calling `good`, `eof`, `fail` and `bad`. See member type `iostate`.
State	exception mask	`exceptions`	The state flags for which a failure exception is thrown. See member type `iostate`.
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*`.
	tied stream	`tie`	Pointer to output stream that is flushed before each i/o operation on this stream.
	stream buffer	`rdbuf`	Pointer to the associated `basic_streambuf` object, which is charge of all input/output operations.

Template parameters

charT: Character type.
This shall be a non-array POD type.
Aliased as member type basic_istream::char_type.
traits: Character traits class that defines essential properties of the characters used by stream objects (see char_traits).
traits::char_type shall be the same as charT.
Aliased as member type basic_istream::traits_type.

Template instantiations

ostream: Output Stream (class)

wostream: Output stream (wide) (class)

These instantiations are declared in <ostream>, which is included by reference in <iostream>.

Member types

The class contains the following member class:

sentry: Prepare stream for output (public member class)

Along with the following member types:

member type	definition	notes
`char_type`	The first template parameter (`charT`)
`traits_type`	The second template parameter (`traits`)	defaults to: `char_traits<charT>`
`int_type`	`traits_type::int_type`
`pos_type`	`traits_type::pos_type`	generally, the same as `streampos`
`off_type`	`traits_type::off_type`	generally, the same as `streamoff`

And these member types inherited from ios_base through basic_ios:

event: Type to indicate event type (public member type)

event_callback: Event callback function type (public member type)

failure: Base class for stream exceptions (public member class)

fmtflags: Type for stream format flags (public member type)

Init: Initialize standard stream objects (public member class)

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)

Public member functions

(constructor): Construct object (public member function)

(destructor): Destroy object (public member function)

Formatted output:

operator<<: Insert formatted output (public member function)

Unformatted output:

put: Put character (public member function)

write: Write block of data (public member function)

Positioning:

tellp: Get position in output sequence (public member function)

seekp: Set position in output sequence (public member function)

Synchronization:

flush: Flush output stream buffer (public member function)

Protected member functions

operator=: Move assignment (protected member function)

swap: Swap internals (protected member function)

Public member functions inherited from `basic_ios`

good: Check whether state of stream is good (public member function)

eof: Check whether eofbit is set (public member function)

fail: Check whether failbit or badbit is set (public member function)

bad: Check whether badbit is set (public member function)

operator!: Evaluate stream (not) (public member function)

operator bool: Evaluate stream (public member function)

rdstate: Get error state flags (public member function)

setstate: Set error state flag (public member function)

clear: Set error state flags (public member function)

copyfmt: Copy formatting information (public member function)

fill: Get/set fill character (public member function)

exceptions: Get/set exceptions mask (public member function)

imbue: Imbue locale (public member function)

tie: Get/set tied stream (public member function)

rdbuf: Get/set stream buffer (public member function)

narrow: Narrow character (public member function)

widen: Widen character (public member function)

Public member functions inherited from `ios_base`

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)

imbue: Imbue locale (public member function)

getloc: Get current locale (public member function)

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)

register_callback: Register event callback function (public member function)

sync_with_stdio: Toggle synchronization with cstdio streams [static] (public static member function)