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 LegacyOutputIterator 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
iterator_category std::output_iterator_tag
value_type void


(until C++20)


(since C++20)
pointer void
reference void
char_type CharT
traits_type Traits
ostream_type std::basic_ostream<CharT, Traits>

Member types iterator_category, value_type, difference_type, pointer and reference are required to be obtained by inheriting from std::iterator<std::output_iterator_tag, void, void, void, void>.

(until C++17)

Member functions

constructs a new ostream_iterator
(public member function)
destructs an ostream_iterator
(public member function)
writes a object to the associated output sequence
(public member function)
(public member function)
(public member function)


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



See also

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

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