std::unordered_multimap::operator=

 

C++

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Concepts

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Regular expressions library (C++11)

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Containers library

array (C++11)

vector

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forward_list (C++11)

list

set

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multimap

unordered_set (C++11)

unordered_multiset (C++11)

unordered_map (C++11)

unordered_multimap (C++11)

stack

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std::unordered_multimap

Member functions

unordered_multimap::unordered_multimap

unordered_multimap::~unordered_multimap

unordered_multimap::operator=

unordered_multimap::get_allocator

Iterators

unordered_multimap::begin unordered_multimap::cbegin

unordered_multimap::end unordered_multimap::cend

Capacity

unordered_multimap::erase

unordered_multimap::size

unordered_multimap::max_size

Modifiers

unordered_multimap::clear

unordered_multimap::insert

unordered_multimap::emplace

unordered_multimap::emplace_hint

unordered_multimap::erase

unordered_multimap::swap

Lookup

unordered_multimap::count

unordered_multimap::find

unordered_multimap::equal_range

Bucket interface

unordered_multimap::begin2

unordered_multimap::end2

unordered_multimap::bucket_count

unordered_multimap::max_bucket_count

unordered_multimap::bucket_size

unordered_multimap::bucket

Hash policy

unordered_multimap::load_factor

unordered_multimap::max_load_factor

unordered_multimap::rehash

unordered_multimap::reserve

Observers

unordered_multimap::hash_function

unordered_multimap::key_eq

 

unordered_multimap& operator=( const unordered_multimap& other );	(1)	(since C++11)
unordered_multimap& operator=( unordered_multimap&& other );	(2)	(since C++11)

Replaces the contents of the container.

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

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.

Parameters

other

-

another container to be used as source

Return value

*this

Complexity

1) Linear in the size of the container.

2) Constant.

Example

The following code uses to assign one std::unordered_multimap to another:

run this code

#include <unordered_map>
#include <iostream>
 
void display_sizes(const std::unordered_multimap<int, int> &nums1,
                   const std::unordered_multimap<int, int> &nums2,
                   const std::unordered_multimap<int, int> &nums3)
{
    std::cout << "nums1: " << nums1.size() 
              << " nums2: " << nums2.size()
              << " nums3: " << nums3.size() << '\n';
}
 
int main()
{
    std::unordered_multimap<int, int> nums1 {{3, 1}, {4, 1}, {5, 9}};
    std::unordered_multimap<int, int> nums2;
    std::unordered_multimap<int, 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

See also

(constructor)	constructs the unordered_multimap (public member function)