operator==,!=,<,<=,>,>=,<=>(std::reverse_iterator)
| (1) | ||
template< class Iterator1, class Iterator2 >
bool operator==( const std::reverse_iterator<Iterator1>& lhs,
const std::reverse_iterator<Iterator2>& rhs ); |
(until C++17) | |
template< class Iterator1, class Iterator2 >
constexpr bool operator==( const std::reverse_iterator<Iterator1>& lhs,
const std::reverse_iterator<Iterator2>& rhs ); |
(since C++17) | |
| (2) | ||
template< class Iterator1, class Iterator2 >
bool operator!=( const std::reverse_iterator<Iterator1>& lhs,
const std::reverse_iterator<Iterator2>& rhs ); |
(until C++17) | |
template< class Iterator1, class Iterator2 >
constexpr bool operator!=( const std::reverse_iterator<Iterator1>& lhs,
const std::reverse_iterator<Iterator2>& rhs ); |
(since C++17) | |
| (3) | ||
template< class Iterator1, class Iterator2 >
bool operator<( const std::reverse_iterator<Iterator1>& lhs,
const std::reverse_iterator<Iterator2>& rhs ); |
(until C++17) | |
template< class Iterator1, class Iterator2 >
constexpr bool operator<( const std::reverse_iterator<Iterator1>& lhs,
const std::reverse_iterator<Iterator2>& rhs ); |
(since C++17) | |
| (4) | ||
template< class Iterator1, class Iterator2 >
bool operator<=( const std::reverse_iterator<Iterator1>& lhs,
const std::reverse_iterator<Iterator2>& rhs ); |
(until C++17) | |
template< class Iterator1, class Iterator2 >
constexpr bool operator<=( const std::reverse_iterator<Iterator1>& lhs,
const std::reverse_iterator<Iterator2>& rhs ); |
(since C++17) | |
| (5) | ||
template< class Iterator1, class Iterator2 >
bool operator>( const std::reverse_iterator<Iterator1>& lhs,
const std::reverse_iterator<Iterator2>& rhs ); |
(until C++17) | |
template< class Iterator1, class Iterator2 >
constexpr bool operator>( const std::reverse_iterator<Iterator1>& lhs,
const std::reverse_iterator<Iterator2>& rhs ); |
(since C++17) | |
| (6) | ||
template< class Iterator1, class Iterator2 >
bool operator>=( const std::reverse_iterator<Iterator1>& lhs,
const std::reverse_iterator<Iterator2>& rhs ); |
(until C++17) | |
template< class Iterator1, class Iterator2 >
constexpr bool operator>=( const std::reverse_iterator<Iterator1>& lhs,
const std::reverse_iterator<Iterator2>& rhs ); |
(since C++17) | |
template< class Iterator1, std::three_way_comparable_with<Iterator1> Iterator2 >
constexpr std::compare_three_way_result_t<Iterator1, Iterator2>
operator<=>( const std::reverse_iterator<Iterator1>& lhs,
const std::reverse_iterator<Iterator2>& rhs ); |
(7) | (since C++20) |
Compares the underlying iterators. Inverse comparisons are applied in order to take into account that the iterator order is reversed.
| (1-6) only participate in overload resolution if their underlying comparison expressions (see below) are well-formed and convertible to |
(since C++20) |
Parameters
| lhs, rhs | - | iterator adaptors to compare |
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()
Example
#include <compare>
#include <iostream>
#include <iterator>
int main()
{
int a[] {0, 1, 2, 3};
// ↑ └───── x, y
// └──────── z
std::reverse_iterator<int*>
x { std::rend(a) - std::size(a) },
y { std::rend(a) - std::size(a) },
z { std::rbegin(a) + 1 };
std::cout
<< std::boolalpha
<< "*x == " << *x << '\n' // 3
<< "*y == " << *y << '\n' // 3
<< "*z == " << *z << '\n' // 2
<< "x == y ? " << (x == y) << '\n' // true
<< "x != y ? " << (x != y) << '\n' // false
<< "x < y ? " << (x < y) << '\n' // false
<< "x <= y ? " << (x <= y) << '\n' // true
<< "x == z ? " << (x == z) << '\n' // false
<< "x != z ? " << (x != z) << '\n' // true
<< "x < z ? " << (x < z) << '\n' // true!
<< "x <= z ? " << (x <= z) << '\n' // true
<< "x <=> y == 0 ? " << (x <=> y == 0) << '\n' // true
<< "x <=> y < 0 ? " << (x <=> y < 0) << '\n' // false
<< "x <=> y > 0 ? " << (x <=> y > 0) << '\n' // false
<< "x <=> z == 0 ? " << (x <=> z == 0) << '\n' // false
<< "x <=> z < 0 ? " << (x <=> z < 0) << '\n' // true
<< "x <=> z > 0 ? " << (x <=> z > 0) << '\n' // false
;
}
Output:
*x == 3 *y == 3 *z == 2 x == y ? true x != y ? false x < y ? false x <= y ? false x == z ? false x != z ? true x < z ? true x <= z ? true x <=> y == 0 ? true x <=> y < 0 ? false x <=> y > 0 ? false x <=> z == 0 ? false x <=> z < 0 ? true x <=> z > 0 ? false
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