std::unordered_multiset<Key,Hash,KeyEqual,Allocator>::find

1,2) Finds an element with key equivalent to key

3,4) Finds an element with key that compares equivalent to the value x. This overload participates in overload resolution only if Hash::is_transparent and KeyEqual::is_transparent are valid and each denotes a type. This assumes that such Hash is callable with both K and Key type, and that the KeyEqual is transparent, which, together, allows calling this function without constructing an instance of Key

#include <iostream>
#include <unordered_set>
 
int main()
{
    // Simple comparison demo.
    std::unordered_multiset<int> example{1, 2, 3, 4};
 
    if (auto search = example.find(2); search != example.end())
        std::cout << "Found " << (*search) << '\n';
    else
        std::cout << "Not found\n";
}

Found 2