C++ Unordered_multimap Library - max_load_factor() Function


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Description

The C++ function std::unordered_multimap::max_load_factor() returns the current maximum load factor for the unordered_multimap container.

The load factor is calculated as follows −

load_factor = umm.size() / umm.bucket_count();

Default value of max_load_factor is 1.0

The load factor influences the probability of collision in the hash table. The container uses the value of max_load_factor as the threshold that forces an increase in the number of buckets and thus causing a rehash.

Declaration

Following is the declaration for std::unordered_multimap::max_load_factor() function form std::unordered_map() header.

C++11

float max_load_factor() const noexcept;

Parameters

None

Return value

Returns the maximum load factor.

Exceptions

This member function never throws exception.

Time complexity

Constant i.e. O(1)

Example

The following example shows the usage of std::unordered_multimap::max_load_factor() function.

#include <iostream>
#include <unordered_map>

using namespace std;

int main () {
   unordered_multimap<char, int> umm;

   cout << "max_load_factor = " << umm.max_load_factor() << endl;

   return 0;
}

Let us compile and run the above program, this will produce the following result −

max_load_factor = 1
unordered_map.htm
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