9 Iterators library [iterators]

9.8 Stream iterators [iterators.stream]

9.8.2 Class template ostream_iterator [ostream.iterator]

1

ostream_iterator writes (using operator<<) successive elements onto the output stream from which it was constructed. If it was constructed with charT* as a constructor argument, this string, called a delimiter string, is written to the stream after every T is written. It is not possible to get a value out of the output iterator. Its only use is as an output iterator in situations like

while (first != last)
  *result++ = *first++;
2

ostream_iterator is defined as:

namespace std { namespace experimental { namespace ranges { inline namespace v1 {
  template <class T, class charT = char, class traits = char_traits<charT>>
  class ostream_iterator {
  public:
    typedef ptrdiff_t difference_type;
    typedef charT char_type;
    typedef traits traits_type;
    typedef basic_ostream<charT, traits> ostream_type;
    constexpr ostream_iterator() noexcept;
    ostream_iterator(ostream_type& s) noexcept;
    ostream_iterator(ostream_type& s, const charT* delimiter) noexcept;
    ostream_iterator(const ostream_iterator& x) noexcept;
    ~ostream_iterator();
    ostream_iterator& operator=(const T& value);

    ostream_iterator& operator*();
    ostream_iterator& operator++();
    ostream_iterator& operator++(int);
  private:
    basic_ostream<charT, traits>* out_stream;  // exposition only
    const charT* delim;                        // exposition only
  };
}}}}

9.8.2.1 ostream_iterator constructors and destructor [ostream.iterator.cons.des]

constexpr ostream_iterator() noexcept;

1

Effects: Initializes out_stream and delim with nullptr.

ostream_iterator(ostream_type& s) noexcept;

2

Effects: Initializes out_stream with &s and delim with nullptr.

ostream_iterator(ostream_type& s, const charT* delimiter) noexcept;

3

Effects: Initializes out_stream with &s and delim with delimiter.

ostream_iterator(const ostream_iterator& x) noexcept;

4

Effects: Constructs a copy of x.

~ostream_iterator();

5

Effects: The iterator is destroyed.

9.8.2.2 ostream_iterator operations [ostream.iterator.ops]

ostream_iterator& operator=(const T& value);

1

Effects: Equivalent to: 

*out_stream << value;
if(delim != nullptr)
  *out_stream << delim;
return *this;

ostream_iterator& operator*();

2

Returns: *this.

ostream_iterator& operator++(); ostream_iterator& operator++(int);

3

Returns: *this.