public member type
<unordered_set>

std::unordered_set::bucket_size

size_type bucket_size ( size_type n ) const;
Return bucket size
Returns the number of elements in bucket n.

A bucket is a slot in the container's internal hash table to which elements are assigned based on their hash value.

The number of elements in a bucket influences the time it takes to access a particular element in the bucket. The container automatically increases the number of buckets to keep the load factor (which is the average bucket size) below its max_load_factor.

Parameters

n
Bucket number.
This shall be lower than bucket_count.
Member type size_type is an unsigned integral type.

Return Value

The number of elements in bucket n.

Member type size_type is an unsigned integral type.

Example

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// unordered_set::bucket_size
#include <iostream>
#include <string>
#include <unordered_set>

int main ()
{
  std::unordered_set<std::string> myset =
  { "red", "green", "blue", "yellow", "purple", "pink" };

  unsigned nbuckets = myset.bucket_count();

  std::cout << "myset has " << nbuckets << " buckets:\n";

  for (unsigned i=0; i<nbuckets; ++i) {
    std::cout << "bucket #" << i << " has " << myset.bucket_size(i) << " elements.\n";
  }

  return 0;
}


Possible output:
myset has 7 buckets:
bucket #0 has 1 elements.
bucket #1 has 1 elements.
bucket #2 has 2 elements.
bucket #3 has 0 elements.
bucket #4 has 1 elements.
bucket #5 has 1 elements.
bucket #6 has 0 elements.

Complexity

Linear in the bucket size.

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