std::ostream_iterator

 

C++

Language

Standard library headers

Concepts

Utilities library

Strings library

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Algorithms library

Iterators library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

Filesystem library (C++17)

Technical Specifications

 

Iterator library

Iterator primitives
iterator_traits
input_iterator_tagoutput_iterator_tagforward_iterator_tagbidirectional_iterator_tagrandom_access_iterator_tag
iterator
Iterator adaptors
reverse_iterator move_iterator (C++11) back_insert_iterator front_insert_iterator insert_iterator	make_reverse_iterator (C++14) make_move_iterator (C++11) back_inserter front_inserter inserter
Stream iterators
istream_iterator
ostream_iterator
istreambuf_iterator
ostreambuf_iterator
Iterator operations
advance
distance
prev (C++11)
next (C++11)
Range access
begincbegin (C++11)(C++14)
endcend (C++11)(C++14)
rbegincrbegin (C++14)(C++14)
rendcrend (C++14)(C++14)
Container access
size (C++17)
empty (C++17)
data (C++17)

 

std::ostream_iterator

Member functions

ostream_iterator::ostream_iterator

ostream_iterator::~ostream_iterator

ostream_iterator::operator=

ostream_iterator::operator*

ostream_iterator::operator++ostream_iterator::operator++(int)

 

Defined in header <iterator>
template< class T,           class CharT = char,           class Traits = std::char_traits<CharT> > class ostream_iterator : public std::iterator<std::output_iterator_tag,                                               void, void, void, void>		(until C++17)
template< class T,           class CharT = char,           class Traits = std::char_traits<CharT>> class ostream_iterator;		(since C++17)

std::ostream_iterator is a single-pass OutputIterator that writes successive objects of type T into the std::basic_ostream object for which it was constructed, using operator<<. Optional delimiter string is written to the output stream after every write operation. The write operation is performed when the iterator (whether dereferenced or not) is assigned to. Incrementing the std::ostream_iterator is a no-op.

In a typical implementation, the only data members of std::ostream_iterator are a pointer to the associated std::basic_ostream and a pointer to the first character in the delimiter string.

When writing characters, std::ostreambuf_iterator is more efficient, since it avoids the overhead of constructing and destructing the sentry object once per character.

Member types

Member type	Definition
char_type	CharT
traits_type	Traits
ostream_type	std::basic_ostream<CharT, Traits>

Member functions

(constructor)	constructs a new ostream_iterator (public member function)
(destructor)	destructs an ostream_iterator (public member function)
operator=	writes a object to the associated output sequence (public member function)
operator*	no-op (public member function)
operator++operator++(int)	no-op (public member function)

Member types

Member type	Definition
value_type	void
difference_type	void
pointer	void
reference	void
iterator_category	std::output_iterator_tag

Note: before C++17, these member types are required to be obtained by inheriting from std::iterator<std::output_iterator_tag,void,void,void,void>.

Example

Run this code

#include <iostream>
#include <sstream>
#include <iterator>
#include <numeric>
 
int main()
{
    std::istringstream str("0.1 0.2 0.3 0.4");
    std::partial_sum(std::istream_iterator<double>(str),
                      std::istream_iterator<double>(),
                      std::ostream_iterator<double>(std::cout, " "));
}

Output:

0.1 0.3 0.6 1

See also

ostreambuf_iterator	output iterator that writes to std::basic_streambuf (class template)
istream_iterator	input iterator that reads from std::basic_istream (class template)
std::experimental::ostream_joiner (library fundamentals TS v2)	An output iterator that writes successive elements into an output stream, separating adjacent elements with a delimiter (class template)