operator==,!=,<,<=,>,>=,<=>(std::multimap)
Defined in header <map>
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template< class Key, class T, class Compare, class Alloc > bool operator==( const std::multimap<Key, T, Compare, Alloc>& lhs, |
(1) | |
template< class Key, class T, class Compare, class Alloc > bool operator!=( const std::multimap<Key, T, Compare, Alloc>& lhs, |
(2) | (until C++20) |
template< class Key, class T, class Compare, class Alloc > bool operator<( const std::multimap<Key, T, Compare, Alloc>& lhs, |
(3) | (until C++20) |
template< class Key, class T, class Compare, class Alloc > bool operator<=( const std::multimap<Key, T, Compare, Alloc>& lhs, |
(4) | (until C++20) |
template< class Key, class T, class Compare, class Alloc > bool operator>( const std::multimap<Key, T, Compare, Alloc>& lhs, |
(5) | (until C++20) |
template< class Key, class T, class Compare, class Alloc > bool operator>=( const std::multimap<Key, T, Compare, Alloc>& lhs, |
(6) | (until C++20) |
template< class Key, class T, class Compare, class Alloc > /* see below */ operator<=>( const std::multimap<Key, T, Compare, Alloc>& lhs, |
(7) | (since C++20) |
Compares the contents of two multimap
s.
multimap
's ordering Compare.multimap
s with a function object performing synthesized three-way comparison (see below). The return type is same as the result type of synthesized three-way comparison. This comparison ignores the multimap
's ordering Compare.
Given two const E lvalues lhs and rhs as left hand operand and right hand operand respectively (where E
is std::pair<const Key, T>), synthesized three-way comparison is defined as:
- if std::three_way_comparable_with<E, E> is satisfied, equivalent to lhs <=> rhs;
- otherwise, if comparing two const E lvalues by operator< is well-formed and the result type satisfies
boolean-testable
, equivalent to
lhs < rhs ? std::weak_ordering::less : rhs < lhs ? std::weak_ordering::greater : std::weak_ordering::equivalent
- otherwise, synthesized three-way comparison is not defined, and operator<=> does not participate in overload resolution.
three_way_comparable_with
or boolean-testable
is satisfied but not modeled, or operator< is used but E
and <
do not establish a total order.
The |
(since C++20) |
Contents |
[edit] Parameters
lhs, rhs | - | multimap s whose contents to compare
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-T, Key must meet the requirements of EqualityComparable in order to use overloads (1,2).
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-Key must meet the requirements of LessThanComparable in order to use overloads (3-6). The ordering relation must establish total order.
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[edit] Return value
multimap
s are equal, false otherwise.multimap
s are not equal, false otherwise.[edit] Complexity
multimap
.multimap
.[edit] Example
#include <cassert> #include <map> int main() { std::multimap<int, char> a{{1, 'a'}, {2, 'b'}, {3, 'c'}}; std::multimap<int, char> b{{1, 'a'}, {2, 'b'}, {3, 'c'}}; std::multimap<int, char> c{{7, 'Z'}, {8, 'Y'}, {9, 'X'}, {10, 'W'}}; assert ("" "Compare equal containers:" and (a != b) == false and (a == b) == true and (a < b) == false and (a <= b) == true and (a > b) == false and (a >= b) == true and (a <=> b) != std::weak_ordering::less and (a <=> b) != std::weak_ordering::greater and (a <=> b) == std::weak_ordering::equivalent and "Compare non equal containers:" and (a != c) == true and (a == c) == false and (a < c) == true and (a <= c) == true and (a > c) == false and (a >= c) == false and (a <=> c) == std::weak_ordering::less and (a <=> c) != std::weak_ordering::equivalent and (a <=> c) != std::weak_ordering::greater and ""); }