std::flat_map::extract(3)

NAME
std::flat_map::extract - std::flat_map::extract

Synopsis
   containers extract() &&; (since C++23)
   Extracts adapted containers c. Equivalent to return std::move(c);.
   After this operation *this is empty, even if an exception is thrown.

Parameters
   (none)

Return value
   std::move(c).

Complexity
   Constant.

Example
// Run this code
 #include <cassert>
 #include <flat_map>
 #include <print>
 #include <type_traits>
 #include <vector>
 int main()
 {
     std::flat_map<int, double> map{{1, 1.1}, {2, 2.2}, {3, 3.3}};
     const auto size = map.size();
     auto c = map.extract();
     assert(c.keys.size() == size);
     assert(c.values.size() == size);
     assert(map.empty());
     assert(map.keys().empty());
     assert(map.values().empty());
     // The default keys and values containers are std::vector:
     static_assert(std::is_same_v<decltype(c.keys), std::vector<int>>);
     static_assert(std::is_same_v<decltype(c.value), std::vector<int>>);
     std::println("keys: {}", c.keys);
     std::println("values: {}", c.values);
 }

Output:
 keys: [1, 2, 3]
 values: [1.1, 2.2, 3.3]

See also
   replace replaces the underlying containers
           (public member function)