multimap(); explicit multimap( const Compare& comp, const Allocator& alloc = Allocator() ); | (1) | |
explicit multimap( const Allocator& alloc ); | (1) | (since C++11) |
(2) | ||
template< class InputIt > multimap( InputIt first, InputIt last, const Compare& comp = Compare(), const Allocator& alloc = Allocator() ); | ||
template< class InputIt > multimap( InputIt first, InputIt last, const Allocator& alloc ); | (since C++14) | |
multimap( const multimap& other ); | (3) | |
multimap( const multimap& other, const Allocator& alloc ); | (3) | (since C++11) |
multimap( multimap&& other ); | (4) | (since C++11) |
multimap( multimap&& other, const Allocator& alloc ); | (4) | (since C++11) |
(5) | ||
multimap( std::initializer_list<value_type> init, const Compare& comp = Compare(), const Allocator& alloc = Allocator() ); | (since C++11) | |
multimap( std::initializer_list<value_type> init, const Allocator& ); | (since C++14) |
Constructs new container from a variety of data sources and optionally using user supplied allocator alloc
or comparison function object comp
.
[first, last)
. other
. If alloc
is not provided, allocator is obtained by calling std::allocator_traits<allocator_type>::select_on_container_copy_construction(other.get_allocator())
.other
using move semantics. If alloc
is not provided, allocator is obtained by move-construction from the allocator belonging to other
.init
. alloc | - | allocator to use for all memory allocations of this container |
comp | - | comparison function object to use for all comparisons of keys |
first, last | - | the range to copy the elements from |
other | - | another container to be used as source to initialize the elements of the container with |
init | - | initializer list to initialize the elements of the container with |
Type requirements | ||
-InputIt must meet the requirements of InputIterator. |
||
-Compare must meet the requirements of Compare. |
||
-Allocator must meet the requirements of Allocator. |
N = std::distance(first, last)
in general, linear in N
if the range is already sorted by value_comp()
.other
alloc
is given and alloc != other.get_allocator()
, then linear.N = init.size())
in general, linear in N
if init
is already sorted by value_comp()
.Calls to Allocator::allocate
may throw.
After container move construction (overload (4)), references, pointers, and iterators (other than the end iterator) to other
remain valid, but refer to elements that are now in *this
. The current standard makes this guarantee via the blanket statement in §23.2.1[container.requirements.general]/12, and a more direct guarantee is under consideration via LWG 2321.
#include <iostream> #include <map> struct Point { double x, y; }; struct PointCmp { bool operator()(const Point& lhs, const Point& rhs) const { return lhs.x < rhs.x; // NB. ignores y on purpose } }; int main() { std::multimap<int, int> m = {{1,1},{2,2},{3,3},{4,4},{5,5},{4,4},{3,3},{2,2},{1,1}}; for(auto& p: m) std::cout << p.first << ' ' << p.second << '\n'; // custom comparison std::multimap<Point, double, PointCmp> mag{ { {5, 12}, 13 }, { {3, 4}, 5 }, { {8, 15}, 17 }, { {3, -3}, -1 }, }; for(auto p : mag) std::cout << "The magnitude of (" << p.first.x << ", " << p.first.y << ") is " << p.second << '\n'; }
Output:
1 1 1 1 2 2 2 2 3 3 3 3 4 4 4 4 5 5 The magnitude of (3, 4) is 5 The magnitude of (3, -3) is -1 The magnitude of (5, 12) is 13 The magnitude of (8, 15) is 17
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
DR | Applied to | Behavior as published | Correct behavior |
---|---|---|---|
LWG 2193 | C++11 | the default constructor is explicit | made non-explicit |
assigns values to the container (public member function) |
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