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;

The class template basic_ostream provides support for high level output operations on streams. The supported operations include sequential writing and formatting. This functionality is implemented over the interface, provided by the basic_streambuf class. It is accessed through basic_ios class.

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>

Also several objects are defined in <iostream> header to provide access to the standard output (stdout), the standard error (stderr) and standard log (stdlog) streams: 

extern ostream cout; //stdout 
extern ostream cerr; //stderr
extern ostream clog; //stdlog
 
extern ostream wcout; //stdout (wide character)
extern ostream wcerr; //stderr (wide character)
extern ostream wclog; //stdlog (wide character)

Contents

[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

(constructor)
constructs the object
(public member function)
(destructor) [virtual]
destructs the object
(virtual public member function)
Formatted input
operator<<
inserts formatted data
(public member function)
Unformatted input
put
inserts a character
(public member function)
write
inserts blocks of characters
(public member function)
Positioning
tellp
returns the output position indicator
(public member function)
seekp
sets the output position indicator
(public member function)
Miscellaneous
flush
synchronizes with the underlying storage device
(public member function)

Member classes

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

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
good
checks if no error has occurred i.e. I/O operations are available
(public member function)
eof
checks if end-of-file has been reached
(public member function)
fail
checks if a recoverable error has occurred
(public member function)
bad
checks if a non-recoverable error has occurred
(public member function)
operator!
checks if an error has occurred (synonym of fail())
(public member function)
operator bool
checks if no error has occurred (synonym of good())
(public member function)
rdstate
returns state flags
(public member function)
setstate
sets state flags
(public member function)
clear
clears error and eof flags
(public member function)
Formatting
copyfmt
copies formatting information
(public member function)
fill
manages the fill character
(public member function)
Miscellaneous
exceptions
manages exception mask
(public member function)
imbue
sets the locale
(public member function)
rdbuf
manages associated stream buffer
(public member function)
tie
manages tied stream
(public member function)
narrow
narrows characters
(public member function)
widen
widens characters
(public member function)

Inherited from std::ios_base

Member functions

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

Member types and constants

Type Explanation
openmode
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
fmtflags
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
iostate
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
seekdir
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
event
specifies event type
event_callback
callback function type
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