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

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C++
Iterator library
Iterator concepts
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Algorithm concepts and utilities
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(C++20)
(C++20)
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(C++20)
Iterator adaptors
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(C++11) (C++14)
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(C++17) (C++20)
(C++17)
(C++17)
std::move_iterator
Defined in header <iterator>
template < class Iter1, class Iter2 >

bool operator == ( const std:: move_iterator < Iter1 > & lhs,

const std:: move_iterator < Iter2 > & rhs ) ;
(1) (constexpr since C++17)
template < class Iter1, class Iter2 >

bool operator ! = ( const std:: move_iterator < Iter1 > & lhs,

const std:: move_iterator < Iter2 > & rhs ) ;
(2) (constexpr since C++17)
(until C++20)
template < class Iter1, class Iter2 >

bool operator < ( const std:: move_iterator < Iter1 > & lhs,

const std:: move_iterator < Iter2 > & rhs ) ;
(3) (constexpr since C++17)
template < class Iter1, class Iter2 >

bool operator <= ( const std:: move_iterator < Iter1 > & lhs,

const std:: move_iterator < Iter2 > & rhs ) ;
(4) (constexpr since C++17)
template < class Iter1, class Iter2 >

bool operator > ( const std:: move_iterator < Iter1 > & lhs,

const std:: move_iterator < Iter2 > & rhs ) ;
(5) (constexpr since C++17)
template < class Iter1, class Iter2 >

bool operator >= ( const std:: move_iterator < Iter1 > & lhs,

const std:: move_iterator < Iter2 > & rhs ) ;
(6) (constexpr since C++17)
template < class Iter1, std:: three_way_comparable_with < Iter1 > Iter2 >

constexpr std:: compare_three_way_result_t < Iter1, Iter2 >
operator <=> ( const std:: move_iterator < Iter1 > & lhs,

const std:: move_iterator < Iter2 > & rhs ) ;
(7) (since C++20)

Compares the underlying iterators of lhs and rhs .

1) This overload participates in overload resolution only if lhs. base ( ) == rhs. base ( ) is well-formed and convertible to bool .
3-6) These overloads participate in overload resolution only if lhs. base ( ) < rhs. base ( ) is well-formed and convertible to bool .

The != operator is synthesized from operator== .

(since C++20)

Parameters

lhs, rhs - iterator adaptors to compare

Return value

1) lhs. base ( ) == rhs. base ( )
2) ! ( lhs == rhs )
3) lhs. base ( ) < rhs. base ( )
4) ! ( rhs < lhs )
5) rhs < lhs
6) ! ( lhs < rhs )
7) lhs. base ( ) <=> rhs. base ( )

Example

Run this code 
#include <cassert>
#include <iterator>
 
int main()
{
    int a[]{9, 8, 7, 6};
    //            │  └───── x, y
    //            └──────── z
 
    // “x” and “y” are equal, but “x” is greater than “z”
    std::move_iterator<int*>
        x{std::end(a) - 1},
        y{std::end(a) - 1},
        z{std::end(a) - 2};
 
    // two-way comparisons
    assert(  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 comparisons
    assert(  x <=> y == 0 );
    assert(!(x <=> y <  0));
    assert(!(x <=> y >  0));
    assert(!(x <=> z == 0));
    assert(!(x <=> z <  0));
    assert(  x <=> z >  0 );
}

See also

(C++20)
compares the underlying iterator and the underlying sentinel
(function template)
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