std::unordered_map - cppreference.com
Apr 26, 2025 · std::unordered_map is an associative container that contains key-value pairs with unique keys. Search, insertion, and removal of elements have average constant-time …
std::unordered_set - cppreference.com
Apr 26, 2025 · std::unordered_set meets the requirements of Container, AllocatorAwareContainer, UnorderedAssociativeContainer. All member functions of std::unordered_set are constexpr : it …
std::unordered_set<Key,Hash,KeyEqual,Allocator>:: unordered_set
Nov 21, 2021 · unordered_set (std:: initializer_list < value_type > init, size_type bucket_count, const Allocator & alloc ) : unordered_set (init, bucket_count, Hash (), key_equal (), alloc) {}
Standard library header <unordered_set> (C++11) - Reference
Nov 27, 2023 · namespace std {template < class Key, class Hash = hash < Key >, class Pred = equal_to < Key >, class Allocator = allocator < Key >> class unordered_multiset {public: // …
std::unordered_multimap - cppreference.com
Apr 26, 2025 · std::unordered_multimap is an unordered associative container that supports equivalent keys (an unordered_multimap may contain multiple copies of each key value) and …
std::unordered_map<Key,T,Hash,KeyEqual,Allocator>:: emplace
Dec 4, 2021 · If value_type is not EmplaceConstructible into unordered_map from args, the behavior is undefined. If after the operation the new number of elements is greater than old …
std::unordered_set<Key,Hash,KeyEqual,Allocator>:: insert - Reference
May 9, 2025 · The value_type must be EmplaceConstructible into unordered_set from std:: forward < K > (obj). This overload participates in overload resolution only if Hash and …
std::unordered_set<Key,Hash,KeyEqual,Allocator>:: contains
Nov 5, 2023 · #include <iostream> #include <unordered_set> int main {std:: unordered_set < int > example {1, 2, 3, 4}; for (int x : {2, 5}) if (example. contains (x)) std:: cout << x <<": Found \\n "; …
Standard library header <unordered_map> (C++11) - Reference
Nov 27, 2023 · namespace std {template < class Key, class T, class Hash = hash < Key >, class Pred = equal_to < Key >, class Allocator = allocator < pair < const Key, T >>> class …
C++ named requirements: UnorderedAssociativeContainer (since …
Nov 21, 2024 · Unordered associative containers meet the requirements of AllocatorAwareContainer. For std::unordered_map and std::unordered_multimap the …