std::flat_map<Key,T,Compare,KeyContainer,MappedContainer>::insert_or_assign - cppreference.com (original) (raw)
| template< class M > std::pair<iterator, bool> insert_or_assign( const key_type& k, M&& obj ); | (1) | (since C++23) |
|---|---|---|
| template< class M > std::pair<iterator, bool> insert_or_assign( key_type&& k, M&& obj ); | (2) | (since C++23) |
| template< class K, class M > std::pair<iterator, bool> insert_or_assign( K&& k, M&& obj ); | (3) | (since C++23) |
| template< class M >iterator insert_or_assign( const_iterator hint, const key_type& k, M&& obj ); | (4) | (since C++23) |
| template< class M >iterator insert_or_assign( const_iterator hint, key_type&& k, M&& obj ); | (5) | (since C++23) |
| template< class K, class M >iterator insert_or_assign( const_iterator hint, K&& k, M&& obj ); | (6) | (since C++23) |
The conversion from k into key_type must construct an object u, for which find(k) == find(u) is true. Otherwise, the behavior is undefined.
[edit] Parameters
| k | - | the key used both to look up and to insert if not found |
|---|---|---|
| hint | - | iterator to the position before which the new element will be inserted |
| obj | - | the value to insert or assign |
[edit] Return value
1-3) The bool component is true if the insertion took place and false if the assignment took place. The iterator component is pointing at the element that was inserted or updated.
4-6) Iterator pointing at the element that was inserted or updated.
[edit] Complexity
[edit] Notes
insert_or_assign returns more information than operator[] and does not require default-constructibility of the mapped type.
[edit] Example
#include #include #include void print_node(const auto& node) { std::cout << '[' << node.first << "] = " << node.second << '\n'; } void print_result(auto const& pair) { std::cout << (pair.second ? "inserted: " : "assigned: "); print_node(*pair.first); } int main() { std::flat_map<std::string, std::string> map; print_result(map.insert_or_assign("a", "apple")); print_result(map.insert_or_assign("b", "banana")); print_result(map.insert_or_assign("c", "cherry")); print_result(map.insert_or_assign("c", "clementine")); for (const auto& node : map) print_node(node); }
Output:
inserted: [a] = apple inserted: [b] = banana inserted: [c] = cherry assigned: [c] = clementine [a] = apple [b] = banana [c] = clementine
[edit] See also
| | access or insert specified element (public member function) [edit] | | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | | access specified element with bounds checking (public member function) [edit] | | | inserts elements (public member function) [edit] | | | constructs element in-place (public member function) [edit] | | | inserts in-place if the key does not exist, does nothing if the key exists (public member function) [edit] |