std::unordered_multiset<Key,Hash,KeyEqual,Allocator>:: find
From cppreference.com
<
cpp
|
container
|
unordered multiset
|
iterator find
(
const
Key
&
key
)
;
|
(1) | (since C++11) |
|
const_iterator find
(
const
Key
&
key
)
const
;
|
(2) | (since C++11) |
|
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
. If there are several elements with the requested key in the container, any of them may be returned.
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
An iterator to the requested element. 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
Run this code
#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"; }
Output:
Found 2
See also
|
returns the number of elements matching specific key
(public member function) |
|
|
returns range of elements matching a specific key
(public member function) |