unordered_map max_bucket_count in C++ STL

The unordered_map::max_bucket_count is a built in function in C++ STL. It returns the maximum number of buckets unordered_map container can have.

Syntax

unordered_map.max_bucket_count()

Parameters : It does not accept any parameter.

Return Type : Returns maximum number of buckets. Return type is an unsigned integer.

Example-1:

// C++ program to illustrate the
// unordered_map::max_bucket_count function
#include <bits/stdc++.h>
using namespace std;

int main()
{

    // declaration of unordered_map
    unordered_map<int, int> sample;

    cout << "Size is : " << sample.size() << endl;
    cout << "Max bucket count is : " << sample.max_bucket_count() << endl;

    // insert elements
    sample.insert({ 5, 10 });
    sample.insert({ 10, 10 });
    sample.insert({ 15, 10 });
    sample.insert({ 20, 10 });
    sample.insert({ 21, 10 });

    cout << "Size is : " << sample.size() << endl;
    cout << "Max bucket count is : " << sample.max_bucket_count() << endl;
    return 0;
}

Output:

Size is : 0
Max bucket count is : 1152921504606846975
Size is : 5
Max bucket count is : 1152921504606846975

Example-2:

// C++ program to illustrate the
// unordered_map::max_bucket_count function
#include <bits/stdc++.h>
using namespace std;

int main()
{

    // declaration of unordered_map
    unordered_map<char, int> sample;

    cout << "Size is : " << sample.size() << endl;
    cout << "Max bucket count is : " << sample.max_bucket_count() << endl;

    // insert elements
    sample.insert({ 'a', 10 });
    sample.insert({ 'b', 10 });
    sample.insert({ 'c', 10 });
    sample.insert({ 'd', 10 });
    sample.insert({ 'e', 10 });
    sample.insert({ 'f', 10 });

    cout << "Size is : " << sample.size() << endl;
    cout << "Max bucket count is : " << sample.max_bucket_count() << endl;
    return 0;
}

Output:

Size is : 0
Max bucket count is : 1152921504606846975
Size is : 6
Max bucket count is : 1152921504606846975

Complexity: Its Complexity is constant.