27 Iterators library [iterators]

27.6 Stream iterators [stream.iterators]

27.6.4 Class template ostreambuf_­iterator [ostreambuf.iterator]

namespace std {
  template<class charT, class traits = char_traits<charT>>
  class ostreambuf_iterator {
  public:
    using iterator_category = output_iterator_tag;
    using value_type        = void;
    using difference_type   = void;
    using pointer           = void;
    using reference         = void;
    using char_type         = charT;
    using traits_type       = traits;
    using streambuf_type    = basic_streambuf<charT,traits>;
    using ostream_type      = basic_ostream<charT,traits>;

    ostreambuf_iterator(ostream_type& s) noexcept;
    ostreambuf_iterator(streambuf_type* s) noexcept;
    ostreambuf_iterator& operator=(charT c);

    ostreambuf_iterator& operator*();
    ostreambuf_iterator& operator++();
    ostreambuf_iterator& operator++(int);
    bool failed() const noexcept;

  private:
    streambuf_type* sbuf_;                // exposition only
  };
}
The class template ostreambuf_­iterator writes successive characters onto the output stream from which it was constructed.
It is not possible to get a character value out of the output iterator.

27.6.4.1 ostreambuf_­iterator constructors [ostreambuf.iter.cons]

ostreambuf_iterator(ostream_type& s) noexcept;
Requires: s.rdbuf() shall not be a null pointer.
Effects: Initializes sbuf_­ with s.rdbuf().
ostreambuf_iterator(streambuf_type* s) noexcept;
Requires: s shall not be a null pointer.
Effects: Initializes sbuf_­ with s.

27.6.4.2 ostreambuf_­iterator operations [ostreambuf.iter.ops]

ostreambuf_iterator& operator=(charT c);
Effects: If failed() yields false, calls sbuf_­->sputc(c); otherwise has no effect.
Returns: *this.
ostreambuf_iterator& operator*();
Returns: *this.
ostreambuf_iterator& operator++(); ostreambuf_iterator& operator++(int);
Returns: *this.
bool failed() const noexcept;
Returns: true if in any prior use of member operator=, the call to sbuf_­->sputc() returned traits​::​eof(); or false otherwise.