std::multiset::operator=
From cppreference.com
multiset& operator=( const multiset& other );
|
(1) | |
multiset& operator=( multiset&& other );
|
(2) | (since C++11) |
multiset& operator=( std::initializer_list<value_type> ilist );
|
(3) | (since C++11) |
Replaces the contents of the container.
1) Copy assignment operator. Replaces the contents with a copy of the contents of
other
.If std::allocator_traits<allocator_type>::propagate_on_container_copy_assignment() is true, the target allocator is replaced by a copy of the source allocator. If the target and the source allocators do not compare equal, the target (*this) allocator is used to deallocate the memory, then other
's allocator is used to allocate it before copying the elements. (since C++11)
2) Move assignment operator. Replaces the contents with those of
other
using move semantics (i.e. the data in other
is moved from other
into this container). other
is in a valid but unspecified state afterwards. If std::allocator_traits<allocator_type>::propagate_on_container_move_assignment() is true, the target allocator is replaced by a copy of the source allocator. If it is false and the source and the target allocators do not compare equal, the target cannot take ownership of the source memory and must move-assign each element individually, allocating additional memory using its own allocator as needed.
3) Replaces the contents with those identified by initializer list
ilist
.
Contents |
[edit] Parameters
other | - | another container to use as data source |
ilist | - | initializer list to use as data source |
[edit] Return value
*this
[edit] Complexity
1) Linear in the size of the
other
.
2) Constant unless std::allocator_traits<allocator_type>::propagate_on_container_move_assignment() is false and the allocators do not compare equal (in which case linear).
3) Linear in the size of
ilist
.
Exceptions
2)
noexcept specification:
noexcept(std::allocator_traits<Allocator>::is_always_equal::value
&& std::is_nothrow_move_assignable<Compare>::value) |
(since C++17) |
[edit] Example
The following code uses to assign one std::multiset to another:
Run this code
#include <set> #include <iostream> void display_sizes(const std::multiset<int> &nums1, const std::multiset<int> &nums2, const std::multiset<int> &nums3) { std::cout << "nums1: " << nums1.size() << " nums2: " << nums2.size() << " nums3: " << nums3.size() << '\n'; } int main() { std::multiset<int> nums1 {3, 1, 4, 6, 5, 9}; std::multiset<int> nums2; std::multiset<int> nums3; std::cout << "Initially:\n"; display_sizes(nums1, nums2, nums3); // copy assignment copies data from nums1 to nums2 nums2 = nums1; std::cout << "After assigment:\n"; display_sizes(nums1, nums2, nums3); // move assignment moves data from nums1 to nums3, // modifying both nums1 and nums3 nums3 = std::move(nums1); std::cout << "After move assigment:\n"; display_sizes(nums1, nums2, nums3); }
Output:
Initially: nums1: 6 nums2: 0 nums3: 0 After assigment: nums1: 6 nums2: 6 nums3: 0 After move assigment: nums1: 0 nums2: 6 nums3: 6
[edit] See also
constructs the multiset (public member function) |