public member function
<unordered_set>

std::unordered_set::load_factor

float load_factor() const noexcept;
Return load factor
Returns the current load factor in the unordered_set container.

The load factor is the ratio between the number of elements in the container (its size) and the number of buckets (bucket_count):

load_factor = size / bucket_count

The load factor influences the probability of collision in the hash table (i.e., the probability of two elements being located in the same bucket). The container automatically increases the number of buckets to keep the load factor below a specific threshold (its max_load_factor), causing a rehash each time an expansion is needed.

To retrieve or change this threshold, use member function max_load_factor.

Parameters

none

Return Value

The current load factor.

Example

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// unordered_set hash table stats
#include <iostream>
#include <unordered_set>

int main ()
{
  std::unordered_set<int> myset;

  std::cout << "size = " << myset.size() << std::endl;
  std::cout << "bucket_count = " << myset.bucket_count() << std::endl;
  std::cout << "load_factor = " << myset.load_factor() << std::endl;
  std::cout << "max_load_factor = " << myset.max_load_factor() << std::endl;

  return 0;
}


Possible output:
size = 0
bucket_count = 11
load_factor = 0
max_load_factor = 1

Complexity

Constant.

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