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

From cppreference.com
 
 
 
 
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 only participates in overload resolution 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.

Contents

[edit] Parameters

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

[edit] 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.

[edit] Complexity

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

[edit] Example

#include <iostream>
#include <unordered_map>
 
int main()
{  
// simple comparison demo
    std::unordered_map<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

[edit] See also

returns the number of elements matching specific key
(public member function) [edit]
returns range of elements matching a specific key
(public member function) [edit]