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std::forward_iterator(3)      C++ Standard Libary     std::forward_iterator(3)

NAME
       std::forward_iterator - std::forward_iterator

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

	      concept forward_iterator =
		  std::input_iterator<I> &&
		  std::derived_from</*ITER_CONCEPT*/<I>,
       (since C++20)
	  std::forward_iterator_tag> &&
		  std::incrementable<I>	&&

		  std::sentinel_for<I, I>;

	  This	concept	 refines  std::input_iterator by requiring that	I also
       model
	  std::incrementable (thereby making it	suitable for multi-pass	 algo-
       rithms),	and
	  guaranteeing	that  two  iterators to	the same range can be compared
       against each
	  other.

Notes
	  Unlike the LegacyForwardIterator requirements, the  forward_iterator
       concept does not
	  require dereference to return	a reference.

Example
	  A minimum forward iterator.

	#include <cstddef>
	#include <iterator>

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

	    int	operator*() const;

	    SimpleForwardIterator& operator++();

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

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

	static_assert(std::forward_iterator<SimpleForwardIterator>);

See also
				 specifies  that  a type is an input iterator,
       that is,	its
	  input_iterator	 referenced values can be read and it  can  be
       both pre- and
	  (C++20)		 post-incremented
				 (concept)
	  bidirectional_iterator  specifies that a forward_iterator is a bidi-
       rectional
	  (C++20)		 iterator, supporting movement backwards
				 (concept)

http://cppreference.com		  2024.06.10	      std::forward_iterator(3)

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