public member function
<unordered_map>

std::unordered_multimap::bucket

size_type bucket ( const key_type& k ) const;
Locate element's bucket
Returns the bucket number where the elements with key k are located.

A bucket is a slot in the container's internal hash table to which elements are assigned based on the hash value of their key. Elements with the same key are located in the same bucket. Buckets are numbered from 0 to (bucket_count-1).

Individual elements in a bucket can be accessed by means of the range iterators returned by unordered_multimap::begin and unordered_multimap::end.

Parameters

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

Return value

The order number of the bucket corresponding to k.

Member type size_type is an unsigned integral type.

Example

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// unordered_multimap::bucket
#include <iostream>
#include <string>
#include <unordered_map>

int main ()
{
  std::unordered_multimap<std::string,std::string> myumm = {
    {"John","Middle East"},
    {"John","Africa"},
    {"Adam","Europe"},
    {"Bill","Norh-America"}
  };

  for (auto& x: myumm) {
    std::cout << "Element [" << x.first << ":" << x.second << "]";
    std::cout << " is in bucket #" << myumm.bucket (x.first) << std::endl;
  }

  return 0;
}


Possible output:
Element [Adam:Europe] is in bucket #1
Element [John:Middle East] is in bucket #1
Element [John:Africa] is in bucket #1
Element [Bill:North-America] is in bucket #2

Complexity

Constant.

Iterator validity

No changes.

See also

  • 9316991614 2018-02-25
  • 191841613 2018-02-25
  • 16411612 2018-02-25
  • 6081981611 2018-02-25
  • 1784561610 2018-02-25
  • 4651609 2018-02-25
  • 9348111608 2018-02-25
  • 2513771607 2018-02-25
  • 6478461606 2018-02-24
  • 4985791605 2018-02-24
  • 5637141604 2018-02-24
  • 282181603 2018-02-24
  • 6217941602 2018-02-24
  • 5076141601 2018-02-24
  • 714281600 2018-02-24
  • 6607141599 2018-02-24
  • 949041598 2018-02-24
  • 6809961597 2018-02-24
  • 671871596 2018-02-24
  • 7107821595 2018-02-24