std::unordered_multimap<Key,T,Hash,KeyEqual,Allocator>::find

`iterator find( const Key& key );`	(1)
`const_iterator find( const Key& key ) const;`	(2)
`template< class K > iterator find( const K& x );`	(3)	(since C++20)
`template< class K > const_iterator find( const K& x ) const;`	(4)	(since C++20)

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.

Parameters

key	-	key value of the element to search for
x	-	a value of any type that can be transparently compared with a key

Return value

Iterator to an element with key equivalent to key. If no such element is found, past-the-end (see end()) iterator is returned.

Complexity

Constant on average, worst case linear in the size of the container.

Notes

Feature-test macro	Value	Std	Feature
`__cpp_lib_generic_unordered_lookup`	201811L	(C++20)	Heterogeneous comparison lookup in unordered associative containers; overloads (3,4)

Example

#include <iostream>
#include <unordered_map>
 
 
 
int main()
{
    // Simple comparison demo.
    std::unordered_multimap<int,char> example = {{1,'a'}, {2,'b'}};
 
    if (auto search = example.find(2); search != example.end())
        std::cout << "Found " << search->first << ' ' << search->second << '\n';
    else
        std::cout << "Not found\n";
 
 
 
 
}

Output:

Found 2 b

count	returns the number of elements matching specific key (public member function)
equal_range	returns range of elements matching a specific key (public member function)

Docs

Docs4dev

Title here