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 complexity.
std:: unordered_set - cppreference.com
Apr 26, 2025 · std::unordered_set is an associative container that contains a set of unique objects of type Key. Search, insertion, and removal have average constant-time complexity.
std::unordered_map<Key,T,Hash,KeyEqual,Allocator>:: unordered_map
Nov 29, 2021 · Define a const == operator for the class/struct and specialize std::hash// structure in the std namespacestd::unordered_map<std::string>={{(1)"One"}{2"Two"}{3"Three"}};// Option 3: Use …
Standard library header <unordered_set> (C++11) - Reference
Nov 27, 2023 · unordered_multiset (unordered_multiset &&); explicit unordered_multiset (const Allocator &); unordered_multiset (const unordered_multiset &, const type_identity_t <Allocator>&);
std::unordered_map<Key,T,Hash,KeyEqual,Allocator>:: find
Dec 4, 2021 · (C++17) Lookup unordered_map::at unordered_map::operator [] unordered_map::count unordered_map::find unordered_map::contains (C++20) unordered_map::equal_range Bucket …
std::unordered_set<Key,Hash,KeyEqual,Allocator>:: contains
Nov 5, 2023 · #include <iostream>#include <unordered_set>int(){std::unordered_set<int>{1234};for(int:{25})if(contains())std::cout<<<<": …
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 that associates …
std::unordered_map<Key,T,Hash,KeyEqual,Allocator>:: merge
Nov 29, 2021 · unordered_map::merge (C++17) unordered_map::insert unordered_map::insert_range (C++23) unordered_map::insert_or_assign (C++17) unordered_map::emplace …
Containers library - cppreference.com
Feb 22, 2025 · Unordered associative containers (since C++11) Unordered associative containers implement unsorted (hashed) data structures that can be quickly searched (O (1) average, O (n) …
std::unordered_set<Key,Hash,KeyEqual,Allocator>:: insert
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 KeyEqual are …