std::basic_ostream

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C++ Standard Library
Input/output library
std::basic_ostream
Defined in header <ostream>

template<

    class CharT,
    class Traits = std::char_traits<CharT>

> class basic_ostream : virtual public std::basic_ios<CharT, Traits>

The class template basic_ostream provides support for high level output operations on character streams. The supported operations include formatted output (e.g. integer values) and unformatted output (e.g. raw characters and character arrays). This functionality is implemented in terms of the interface provided by the basic_streambuf class, accessed through the basic_ios base class. In typical implementations, basic_ostream has no non-inherited data members.

cpp/io/ios base cpp/io/basic iosstd-basic ostream-inheritance.png
About this image

Inheritance diagram

Two specializations for common character types are also defined:

Defined in header <ostream>
Type Definition
ostream basic_ostream<char>
wostream basic_ostream<wchar_t>

Contents

[edit] Global objects

Six global basic_ostream objects are provided by the standard library.

Defined in header <iostream>
writes to the standard C output stream stdout
(global object)
writes to the standard C error stream stderr, unbuffered
(global object)
writes to the standard C error stream stderr
(global object)

[edit] Member types

Member type Definition
char_type CharT
traits_type Traits
int_type Traits::int_type
pos_type Traits::pos_type
off_type Traits::off_type

[edit] Member functions

constructs the object
(public member function)
[virtual]
 destructs the object
(virtual public member function)
(C++11)
 replaces the buffer object
(protected member function)
Formatted input
inserts formatted data
(public member function)
Unformatted input
inserts a character
(public member function)
inserts blocks of characters
(public member function)
Positioning
returns the output position indicator
(public member function)
sets the output position indicator
(public member function)
Miscellaneous
synchronizes with the underlying storage device
(public member function)
(C++11)
 swaps stream objects, except for the associated buffer
(protected member function)

[edit] Member classes

implements basic logic for preparation of the stream for output operations
(public member class)

[edit] Non-member functions

inserts character data
(function)

Inherited from std::basic_ios

Member types

Member type Definition
char_type CharT
traits_type Traits
int_type Traits::int_type
pos_type Traits::pos_type
off_type Traits::off_type
State functions
checks if no error has occurred i.e. I/O operations are available
(public member function)
checks if end-of-file has been reached
(public member function)
checks if a recoverable error has occurred
(public member function)
checks if a non-recoverable error has occurred
(public member function)
checks if an error has occurred (synonym of fail())
(public member function)
checks if no error has occurred (synonym of good())
(public member function)
returns state flags
(public member function)
sets state flags
(public member function)
clears error and eof flags
(public member function)
Formatting
copies formatting information
(public member function)
manages the fill character
(public member function)
Miscellaneous
manages exception mask
(public member function)
sets the locale
(public member function)
manages associated stream buffer
(public member function)
manages tied stream
(public member function)
narrows characters
(public member function)
widens characters
(public member function)

Inherited from std::ios_base

Member functions

Formatting
manages format flags
(public member function)
sets specific format flag
(public member function)
clears specific format flag
(public member function)
manages decimal precision of floating point operations
(public member function)
manages field width
(public member function)
Locales
sets locale
(public member function)
returns current locale
(public member function)
Internal extensible array
[static]
 returns an unique index to be used to access elements in the internal extensible array
(public static member function)
accesses specified element in the internal extensible array of long elements
(public member function)
accesses specified element in the internal extensible array of void* elements
(public member function)
Miscellaneous
registers event callback function
(public member function)
[static]
 sets whether C++ and C IO libraries are interoperable
(public static member function)
Member classes
stream exception
(public member class)
initializes standard stream objects
(public member class)

Member types and constants

Type Explanation
stream open mode type

The following constants are also defined:

Constant Explanation
app seek to the end of stream before each write
binary open in binary mode
in open for reading
out open for writing
trunc discard the contents of the stream when opening
ate seek to the end of stream immediately after open
formatting flags type

The following constants are also defined:

Constant Explanation
dec uses decimal base for conversions
oct use octal base for conversions
hex use hexadecimal base for conversions
basefield dec|oct|hex. Useful for masking operations
left left adjustment (adds fill characters to the right)
right right adjustment (adds fill characters to the left)
internal internal adjustment (adds fill characters to the internal designated point)
adjustfield left|right|internal. Useful for masking operations
scientific generate floating point types using scientific notation
fixed generate floating point types using fixed notation
floatfield scientific|fixed. Useful for masking operations
boolalpha insert and extract bool type in alphanumeric format
showbase generate a prefix indicating the numeric base for integer number output
showpoint generate a decimal-point character unconditionally for floating-point number output
showpos generate a + character for non-negative numeric output
skipws skip leading whitespace before certain input operations
unitbuf flush the output after each output operation
uppercase replace certain lowercase letters with their uppercase
equivalents in certain output output operations
state of the stream type

The following constants are also defined:

Constant Explanation
goodbit no error
badbit irrecoverable stream error
failbit input/output operation failed (formatting or extraction error)
eofbit associated input sequence has reached end-of-file
seeking direction type

The following constants are also defined:

Constant Explanation
beg the beginning of a stream
end the ending of a stream
cur the current position of stream position indicator
specifies event type
callback function type
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