std::multiset<Key,Compare,Allocator>::operator=

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std::multiset

Member functions

multiset::multiset
multiset::~multiset

multiset::operator=
multiset::get_allocator

Iterators
multiset::beginmultiset::cbegin (C++11)
multiset::endmultiset::cend (C++11)
multiset::rbeginmultiset::crbegin (C++11)
multiset::rendmultiset::crend (C++11)
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multiset::size
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multiset::key_comp
multiset::value_comp

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multiset::clear
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multiset::insert
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Lookup
multiset::count
multiset::find
multiset::contains (C++20)
multiset::equal_range
multiset::lower_bound
multiset::upper_bound

Non-member functions

std::swap(std::multiset)
erase_if(std::multiset) (C++20)
operator==operator<=> (C++20)

operator!=operator<operator>operator<=operator>=

(until C++20)(until C++20)(until C++20)(until C++20)(until C++20)

Deduction guides(C++17)

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multiset& operator=(const multiset& other);	(1)	(constexpr since C++26)
	(2)
multiset& operator=( multiset&& other);			(since C++11) (until C++17)
multiset& operator=( multiset&& other) noexcept(/* see below */);			(since C++17) (constexpr since C++26)
multiset& operator=(std::initializer_list<value_type> ilist);		(3)	(since C++11) (constexpr since C++26)

Replaces the contents of the container.

Lettraits bestd::allocator_traits<allocator_type>:

1) Copy assignment operator. Replaces the contents with a copy of the contents ofother.

Iftraits::propagate_on_container_copy_assignment::value istrue, the allocator of*this is replaced by a copy ofother. If the allocator of*this after assignment would compare unequal to its old value, the old allocator is used to deallocate the memory, then the new allocator is used to allocate it before copying the elements. Otherwise, the memory owned by*this may be reused when possible. In any case, the elements originally belonging to*this may be either destroyed or replaced by element-wise copy-assignment.

(since C++11)

2) Move assignment operator. Replaces the contents with those ofother using move semantics (i.e. the data inother is moved fromother into this container).other is in a valid but unspecified state afterwards.

Iftraits::propagate_on_container_move_assignment::value istrue, the allocator of*this is replaced by a copy of that ofother. If it isfalse and the allocators of*this andother do not compare equal,*this cannot take ownership of the memory owned byother and must move-assign each element individually, allocating additional memory using its own allocator as needed. In any case, all elements originally belonging to*this are either destroyed or replaced by element-wise move-assignment.

3) Replaces the contents with those identified by initializer listilist.

[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*this andother.

2) Linear in the size of*this unless the allocators do not compare equal and do not propagate, in which case linear in the size of*this andother.

3)\(\scriptsize O(N \cdot \log(N))\)O(N·log(N)) in general, where\(\scriptsize N\)N issize()+ ilist.size(). Linear ifilist is sorted with respect tovalue_comp().

[edit]Exceptions

noexcept specification:

noexcept(std::allocator_traits<Allocator>::is_always_equal::value
&&std::is_nothrow_move_assignable<Compare>::value)

(since C++17)

[edit]Notes

After container move assignment (overload(2)), unless element-wise move assignment is forced by incompatible allocators, references, pointers, and iterators (other than the end iterator) toother remain valid, but refer to elements that are now in*this. The current standard makes this guarantee via the blanket statement in[container.reqmts]/67, and a more direct guarantee is under consideration viaLWG issue 2321.

[edit]Example

The following code usesoperator= to assign onestd::multiset to another:

Run this code

#include <initializer_list>#include <iostream>#include <iterator>#include <set> void print(constauto comment,constauto& container){auto size=std::size(container);std::cout<< comment<<"{ ";for(constauto& element: container)std::cout<< element<<(--size?", ":" ");std::cout<<"}\n";} int main(){std::multiset<int> x{1,2,3}, y, z;constauto w={4,5,6,7}; std::cout<<"Initially:\n";    print("x = ", x);    print("y = ", y);    print("z = ", z); std::cout<<"Copy assignment copies data from x to y:\n";    y= x;    print("x = ", x);    print("y = ", y); std::cout<<"Move assignment moves data from x to z, modifying both x and z:\n";    z= std::move(x);    print("x = ", x);    print("z = ", z); std::cout<<"Assignment of initializer_list w to z:\n";    z= w;    print("w = ", w);    print("z = ", z);}

Output:

Initially:x = { 1, 2, 3 }y = { }z = { }Copy assignment copies data from x to y:x = { 1, 2, 3 }y = { 1, 2, 3 }Move assignment moves data from x to z, modifying both x and z:x = { }z = { 1, 2, 3 }Assignment of initializer_list w to z:w = { 4, 5, 6, 7 }z = { 4, 5, 6, 7 }