home | help 
std::bidire...nal_iterator(3)  C++ Standard Libary std::bidire...nal_iterator(3)

NAME
     std::bidirectional_iterator - std::bidirectional_iterator

Synopsis
	Defined in header <iterator>
	template< class I >

	    concept bidirectional_iterator =
		std::forward_iterator<I> &&
		std::derived_from</*ITER_CONCEPT*/<I>,
	std::bidirectional_iterator_tag>				      &&
     (since C++20)
		requires(I i) {
		    { --i } -> std::same_as<I&>;
		    { i-- } -> std::same_as<I>;

		};

	The concept bidirectional_iterator refines  forward_iterator  by  adding
     the ability to
	move an iterator backward.

Notes
	Unlike	 the   LegacyBidirectionalIterator  requirements,  the	bidirec-
     tional_iterator
	concept does not require dereference to return an lvalue.

Example
	A minimum bidirectional iterator.

      #include <cstddef>
      #include <iterator>

      struct SimpleBidiIterator
      {
	  using difference_type = std::ptrdiff_t;
	  using value_type = int;

	  int operator*() const;

	  SimpleBidiIterator& operator++();

	  SimpleBidiIterator operator++(int)
	  {
	      auto tmp = *this;
	      ++*this;
	      return tmp;
	  }

	  SimpleBidiIterator& operator--();

	  SimpleBidiIterator operator--(int)
	  {
	      auto tmp = *this;
	      --*this;
	      return tmp;
	  }

	  bool operator==(const SimpleBidiIterator&) const;
      };

      static_assert(std::bidirectional_iterator<SimpleBidiIterator>);

See also
	forward_iterator       specifies that an input_iterator is a forward it-
     erator,
	(C++20) 	       supporting equality comparison and multi-pass
			       (concept)
			       specifies that a bidirectional_iterator is a ran-
     dom-access
	random_access_iterator iterator, supporting advancement in constant time
     and
	(C++20) 	       subscripting
			       (concept)

http://cppreference.com 	   2024.06.10	   std::bidire...nal_iterator(3)
home | help