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std::flat_map<Key,T,Compare,KeyContainer,MappedContainer>::replace - cppreference.com

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void replace( key_container_type&& key_cont, mapped_container_type&& mapped_cont );

 (since C++23)

Replaces the underlying containers c. Equivalent to: 

c.keys = std::move(key_cont);
c.values = std::move(mapped_cont);

The following conditions must be met:

  • The expression key_cont.size() == mapped_cont.size() is true,
  • The elements of key_cont are sorted with respect to compare, and
  • key_cont does not contain equal elements.

    Otherwise, the behavior is undefined.

Parameters

keys_cont - a sorted keys container of type KeyContainer, the contents of which will be moved into *this
mapped_cont - a container of mapped values of type MappedContainer, the contents of which will be moved into *this

Return value

(none)

Complexity

Equals to complexity of std::move applied to adapted containers.

Example

#include <algorithm>
#include <cassert>
#include <flat_map>
#include <print>
#include <vector>

int main()
{
    std::vector<int> keys{1, 2, 3};
    assert(std::ranges::is_sorted(keys));
    std::vector<double> values{2.2, 3.3, 1.1};
    assert(keys.size() == values.size());

    std::flat_map<int, double> map;
    assert(map.empty());

    map.replace(keys, values);
    assert(map.size() == 3);
    assert(map.keys() == 3);
    assert(map.values() == 3);
    assert(keys.empty());
    assert(values.empty());

    std::println("{}", map);
}

Output:

See also

extracts the underlying containers
(public member function) [edit]