operator==,!=,<,<=,>,>=,<=>(std::reverse_iterator)

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Iterator library

Iterator concepts

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)

(C++20)

(C++20)

(C++26)

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)

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std::reverse_iterator

Member functions
reverse_iterator::reverse_iterator
reverse_iterator::operator=
reverse_iterator::base
reverse_iterator::operator*reverse_iterator::operator->
reverse_iterator::operator[]
reverse_iterator::operator++reverse_iterator::operator+reverse_iterator::operator+=reverse_iterator::operator--reverse_iterator::operator-reverse_iterator::operator-=
Non-member functions
operator==operator!=operator<operator<=operator>operator>=operator<=> (C++20)
operator+
operator-
iter_move (C++20)
iter_swap (C++20)
make_reverse_iterator (C++14)

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Defined in header`<iterator>`
template<class Iter1,class Iter2> bool operator==(conststd::reverse_iterator<Iter1>& lhs, conststd::reverse_iterator<Iter2>& rhs);	(1)	(constexpr since C++17)
template<class Iter1,class Iter2> bool operator!=(conststd::reverse_iterator<Iter1>& lhs, conststd::reverse_iterator<Iter2>& rhs);	(2)	(constexpr since C++17)
template<class Iter1,class Iter2> bool operator<(conststd::reverse_iterator<Iter1>& lhs, conststd::reverse_iterator<Iter2>& rhs);	(3)	(constexpr since C++17)
template<class Iter1,class Iter2> bool operator<=(conststd::reverse_iterator<Iter1>& lhs, conststd::reverse_iterator<Iter2>& rhs);	(4)	(constexpr since C++17)
template<class Iter1,class Iter2> bool operator>(conststd::reverse_iterator<Iter1>& lhs, conststd::reverse_iterator<Iter2>& rhs);	(5)	(constexpr since C++17)
template<class Iter1,class Iter2> bool operator>=(conststd::reverse_iterator<Iter1>& lhs, conststd::reverse_iterator<Iter2>& rhs);	(6)	(constexpr since C++17)
template<class Iter1,std::three_way_comparable_with<Iter1> Iter2> constexprstd::compare_three_way_result_t<Iter1, Iter2> operator<=>(conststd::reverse_iterator<Iter1>& lhs, conststd::reverse_iterator<Iter2>& rhs);	(7)	(since C++20)

Compares the underlying iterators oflhs andrhs.

The result of equality comparisons are preserved (i.e. equal underlying iterators imply equal reverse iterators).
The result of relational comparisons are reversed (i.e. a greater underlying iterator implies a lesser reverse iterator).

1) This overload participates in overload resolution only iflhs.base()== rhs.base() is well-formed and convertible tobool.

2) This overload participates in overload resolution only iflhs.base()!= rhs.base() is well-formed and convertible tobool.

3) This overload participates in overload resolution only iflhs.base()> rhs.base() is well-formed and convertible tobool.

4) This overload participates in overload resolution only iflhs.base()>= rhs.base() is well-formed and convertible tobool.

5) This overload participates in overload resolution only iflhs.base()< rhs.base() is well-formed and convertible tobool.

6) This overload participates in overload resolution only iflhs.base()<= rhs.base() is well-formed and convertible tobool.

(since C++20)

[edit]Parameters

lhs, rhs

iterator adaptors to compare

[edit]Return value

1)lhs.base()== rhs.base()

2)lhs.base()!= rhs.base()

3)lhs.base()> rhs.base()

4)lhs.base()>= rhs.base()

5)lhs.base()< rhs.base()

6)lhs.base()<= rhs.base()

7)rhs.base()<=> lhs.base()

[edit]Notes

operator<=> returnsrhs.base()<=> lhs.base() rather thanlhs.base()<=> rhs.base() because this is a reverse iterator.

[edit]Example

Run this code

#include <cassert>#include <iterator> int main(){int a[]{0,1,2,3};//            ↑  └───── x, y//            └──────── z// “x” and “y” are equal, but “x” is less than “z” (reversely)std::reverse_iterator<int*>        x{std::rend(a)-std::size(a)},        y{std::rend(a)-std::size(a)},        z{std::rbegin(a)+1}; // two-way comparisonsassert(  x== y);assert(!(x!= y));assert(!(x<  y));assert(  x<= y);assert(!(x== z));assert(  x!= z);assert(  x<  z);assert(  x<= z); // three-way comparisonsassert(  x<=> y==0);assert(!(x<=> y<0));assert(!(x<=> y>0));assert(!(x<=> z==0));assert(  x<=> z<0);assert(!(x<=> z>0));}