public member function
<unordered_map>

std::unordered_map::find

      iterator find ( const key_type& k );
const_iterator find ( const key_type& k ) const;
Get iterator to element
Searches the container for an element with k as key and returns an iterator to it if found, otherwise it returns an iterator to unordered_map::end (the element past the end of the container).

Another member function, unordered_map::count, can be used to just check whether a particular key exists.

The mapped value can also be accessed directly by using member functions at or operator[].

Parameters

k
Key to be searched for.
Member type key_type is the type of the keys for the elements in the container, defined in unordered_map as an alias of its first template parameter (Key).

Return value

An iterator to the element, if the specified key value is found, or unordered_map::end if the specified key is not found in the container.

Member types iterator and const_iterator are forward iterator types.

Example

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
// unordered_map::find
#include <iostream>
#include <string>
#include <unordered_map>

int main ()
{
  std::unordered_map<std::string,double> mymap = {
     {"mom",5.4},
     {"dad",6.1},
     {"bro",5.9} };

  std::string input;
  std::cout << "who? ";
  getline (std::cin,input);

  std::unordered_map<std::string,double>::const_iterator got = mymap.find (input);

  if ( got == mymap.end() )
    std::cout << "not found";
  else
    std::cout << got->first << " is " << got->second;

  std::cout << std::endl;

  return 0;
}


Possible output:
who? dad
dad is 6.1

Complexity

Average case: constant.
Worst case: linear in container size.

Iterator validity

No changes.

See also

  • 9281021542 2018-02-20
  • 632231541 2018-02-20
  • 9751491540 2018-02-20
  • 8333621539 2018-02-20
  • 995001538 2018-02-20
  • 6477441537 2018-02-20
  • 511981536 2018-02-19
  • 2072881535 2018-02-19
  • 6024461534 2018-02-19
  • 7594061533 2018-02-19
  • 9311341532 2018-02-19
  • 4928331531 2018-02-19
  • 38561530 2018-02-19
  • 7776611529 2018-02-19
  • 3038041528 2018-02-19
  • 9566341527 2018-02-19
  • 3936031526 2018-02-19
  • 9531111525 2018-02-19
  • 291211524 2018-02-19
  • 8962001523 2018-02-19