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 testing macro: __cpp_lib_generic_unordered_lookup
(for overloads (3,4)).
Example
#include <iostream> #include <unordered_map> int main() { // simple comparison demo std::unordered_multimap<int,char> example = {{1,'a'},{2,'b'}}; auto search = example.find(2); if (search != example.end()) { std::cout << "Found " << search->first << " " << search->second << '\n'; } else { std::cout << "Not found\n"; } }
Output:
Found 2 b
See also
(C++11)
|
returns the number of elements matching specific key (public member function) |
(C++11)
|
returns range of elements matching a specific key (public member function) |
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