Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. — Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

Header <boost/optional/optional_io.hpp>

Synopsis

#include <istream>
#include <ostream>
#include <boost/optional/optional.hpp>

namespace boost {

template <class CharType, class CharTrait, class T>
  std::basic_ostream<CharType, CharTrait>&
  operator<<(std::basic_ostream<CharType, CharTrait>& out, optional<T> const& v); 

  template <class CharType, class CharTrait>
  std::basic_ostream<CharType, CharTrait>&
  operator<<(std::basic_ostream<CharType, CharTrait>& out, none_t const&); 

template<class CharType, class CharTrait, class T>
  std::basic_istream<CharType, CharTrait>&
  operator>>(std::basic_istream<CharType, CharTrait>& in, optional<T>& v); 

} // namespace boost