std::incrementable_traits

 

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Iterator library

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indirectly_readable (C++20) indirectly_writable (C++20) weakly_incrementable (C++20) incrementable (C++20) is-integer-like is-signed-integer-like (C++20)(C++20)	sentinel_for (C++20) sized_sentinel_for (C++20) input_iterator (C++20) output_iterator (C++20) input_or_output_iterator (C++20)	forward_iterator (C++20) bidirectional_iterator (C++20) random_access_iterator (C++20) contiguous_iterator (C++20)
Iterator primitives
input_iterator_tagoutput_iterator_tagforward_iterator_tagbidirectional_iterator_tagrandom_access_iterator_tagcontiguous_iterator_tag (C++20)	iter_value_titer_difference_titer_reference_titer_const_reference_titer_rvalue_reference_titer_common_reference_t (C++20)(C++20)(C++20)(C++23)(C++20)(C++20)	iterator (deprecated in C++17) iterator_traits incrementable_traits (C++20) indirectly_readable_traits (C++20)
Algorithm concepts and utilities
Indirect callable concepts
indirectly_unary_invocableindirectly_regular_unary_invocable (C++20)(C++20)	indirect_unary_predicate (C++20) indirect_binary_predicate (C++20)	indirect_equivalence_relation (C++20) indirect_strict_weak_order (C++20)
Common algorithm requirements
indirectly_movable (C++20) indirectly_movable_storable (C++20) indirectly_copyable (C++20)	indirectly_copyable_storable (C++20)   indirectly_swappable (C++20) indirectly_comparable (C++20)	permutable (C++20) mergeable (C++20) sortable (C++20)
Utilities
indirect_result_t (C++20)	projected (C++20)	projected_value_t (C++26)
Iterator adaptors
reverse_iterator make_reverse_iterator (C++14) move_iterator (C++11) make_move_iterator (C++11) default_sentinel_tdefault_sentinel (C++20)(C++20) unreachable_sentinel_tunreachable_sentinel (C++20)(C++20)	front_insert_iterator back_insert_iterator inserter insert_iterator front_inserter back_inserter move_sentinel (C++20)	common_iterator (C++20) counted_iterator (C++20) basic_const_iterator (C++23) const_iterator (C++23) const_sentinel (C++23) make_const_iterator (C++23) make_const_sentinel (C++23)
Stream iterators istream_iterator    ostream_iterator istreambuf_iterator ostreambuf_iterator	Iterator customization points ranges::iter_move (C++20) ranges::iter_swap (C++20)
Iterator operations advance distance prev (C++11)   next (C++11) ranges::advance (C++20) ranges::distance (C++20) ranges::prev (C++20) ranges::next (C++20)	Range access begincbegin (C++11)(C++14) rbegincrbegin (C++14)(C++14)   endcend (C++11)(C++14) rendcrend (C++14)(C++14)   sizessize (C++17)(C++20) empty (C++17) data (C++17)

 

Defined in header <iterator>
template< class I > struct incrementable_traits {};	(1)	(since C++20)
template< class T >     requires std::is_object_v<T> struct incrementable_traits<T*>;	(2)	(since C++20)
template< class T > struct incrementable_traits<const T>     : incrementable_traits<T> {};	(3)	(since C++20)
template< class T >     requires requires { typename T::difference_type; } struct incrementable_traits<T>;	(4)	(since C++20)
template< class T >     requires (!requires { typename T::difference_type; }) &&              requires(const T& a, const T& b) { a - b } -> std::integral; } struct incrementable_traits<T>;	(5)	(since C++20)

Computes the associated difference type of the type I, if any. A program may specialize incrementable_traits for a program-defined type.

1) Primary template is an empty struct.

2) Specialization for pointers.

Provides a member type difference_type same as std::ptrdiff_t.

3) Specialization for const-qualified types.

4) Specialization for types that define a public and accessible member type difference_type.

Provides a member type difference_type same as T::difference_type.

5) Specialization for types that do not define a public and accessible member type difference_type but do support subtraction.

Provides a member type difference_type same as std::make_signed_t<decltype(std::declval<T>() - std::declval<T>()>. The implicit expression variations rule (see below) applies to the expression a - b.

Implicit expression variations

A requires expression that uses an expression that is non-modifying for some constant lvalue operand also requires implicit expression variations.

Example

See also

weakly_incrementable (C++20)	specifies that a semiregular type can be incremented with pre- and post-increment operators (concept)
iter_value_titer_reference_titer_const_reference_titer_difference_titer_rvalue_reference_titer_common_reference_t (C++20)(C++20)(C++23)(C++20)(C++20)(C++20)	computes the associated types of an iterator (alias template)
iterator_traits	provides uniform interface to the properties of an iterator (class template)

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