FreeBSD Manual Pages
std::multiset::emplace(3) C++ Standard Libary std::multiset::emplace(3) NAME std::multiset::emplace - std::multiset::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 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 <chrono> #include <cstddef> #include <functional> #include <iomanip> #include <iostream> #include <string> #include <set> class Dew { private: int a, b, c; public: Dew(int _a, int _b, int _c) : a(_a), b(_b), c(_c) {} bool operator<(const Dew& other) const { return (a < other.a) || (a == other.a && b < other.b) || (a == other.a && b == other.b && c < other.c); } }; constexpr int nof_operations{101}; std::size_t set_emplace() { std::multiset<Dew> set; for (int i = 0; i < nof_operations; ++i) for (int j = 0; j < nof_operations; ++j) for (int k = 0; k < nof_operations; ++k) set.emplace(i, j, k); return set.size(); } std::size_t set_insert() { std::multiset<Dew> set; for (int i = 0; i < nof_operations; ++i) for (int j = 0; j < nof_operations; ++j) for (int k = 0; k < nof_operations; ++k) set.insert(Dew(i, j, k)); return set.size(); } void time_it(std::function<int()> set_test, std::string what = "") { const auto start = std::chrono::system_clock::now(); const auto the_size = set_test(); const auto stop = std::chrono::system_clock::now(); const std::chrono::duration<double, std::milli> time = stop - start; if (!what.empty() && the_size) std::cout << std::fixed << std::setprecision(2) << time << " for " << what << '\n'; } int main() { time_it(set_insert, "cache warming..."); time_it(set_insert, "insert"); time_it(set_insert, "insert"); time_it(set_emplace, "emplace"); time_it(set_emplace, "emplace"); } Possible output: 499.61ms for cache warming... 447.89ms for insert 436.77ms for insert 430.62ms for emplace 428.61ms for emplace See also emplace_hint constructs elements in-place using a hint (C++11) (public member function) inserts elements insert or nodes (since C++17) (public member function) http://cppreference.com 2024.06.10 std::multiset::emplace(3)
NAME | Synopsis | Parameters | Return value | Exceptions | Complexity | Example | Possible output: | See also
Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=std::multiset::emplace&sektion=3&manpath=FreeBSD+Ports+15.1.quarterly>