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std::multimap::emplace(3) C++ Standard Libary std::multimap::emplace(3) NAME std::multimap::emplace - std::multimap::emplace Synopsis template< class... Args > (since C++11) iterator emplace( Args&&... args ); Inserts a new element into the container constructed in-place with the given args. The constructor of the new element (i.e. std::pair<const Key, T>) is called with exactly the same arguments as supplied to emplace, forwarded via std::forward<Args>(args).... Careful use of emplace allows the new element to be constructed while avoiding unnecessary copy or move operations. No iterators or references are invalidated. Parameters args - arguments to forward to the constructor of the element Return value An iterator to the inserted element. Exceptions If an exception is thrown for any reason, this function has no ef- fect (strong exception safety guarantee). Complexity Logarithmic in the size of the container. Example // Run this code #include <iostream> #include <string> #include <utility> #include <map> int main() { std::multimap<std::string, std::string> m; // uses pair's move constructor m.emplace(std::make_pair(std::string("a"), std::string("a"))); // uses pair's converting move constructor m.emplace(std::make_pair("b", "abcd")); // uses pair's template constructor m.emplace("d", "ddd"); // emplace with duplicate key m.emplace("d", "DDD"); // uses pair's piecewise constructor m.emplace(std::piecewise_construct, std::forward_as_tuple("c"), std::forward_as_tuple(10, 'c')); for (const auto& p : m) std::cout << p.first << " => " << p.second << '\n'; } Output: a => a b => abcd c => cccccccccc d => ddd d => DDD See also emplace_hint constructs elements in-place using a hint (C++11) (public member function) inserts in-place if the key does not exist, does noth- ing if the key try_emplace exists (public member function) inserts elements insert or nodes (since C++17) (public member function) http://cppreference.com 2024.06.10 std::multimap::emplace(3)
NAME | Synopsis | Parameters | Return value | Exceptions | Complexity | Example | Output: | See also
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