unordered_multimap bucket_count() function in C++ STL (original) (raw)

Last Updated : 8 Aug, 2018

The unordered_multimap::bucket_count() is a built-in function in C++ STL which returns the total number of buckets in the unordered_multimap container. A bucket is a slot in the container's internal hash table to which elements are assigned based on their hash value.Syntax:

unorderedmultimapname.bucket_count()

Parameters: The function does not accept any parameter. Return Value: It returns an unsigned integral type which denotes the total count of buckets. Below programs illustrate the above function: Program 1:

CPP `

// C++ program to illustrate the // unordered_multimap::bucket_count() #include <bits/stdc++.h> using namespace std;

int main() {

// declaration
unordered_multimap<int, int> sample;

// inserts key and element
sample.insert({ 10, 100 });
sample.insert({ 10, 100 });
sample.insert({ 20, 200 });
sample.insert({ 30, 300 });
sample.insert({ 15, 150 });

cout << "The total count of buckets: " 
     << sample.bucket_count();

// prints all element bucket wise
for (int i = 0; i < sample.bucket_count(); i++) {

    cout << "\nBucket " << i << ": ";

    // if bucket is empty
    if (sample.bucket_size(i) == 0)
        cout << "empty";

    for (auto it = sample.cbegin(i); 
              it != sample.cend(i); it++)
        cout << "{" << it->first << ", " 
             << it->second << "}, ";
}
return 0;

}

`

Output:

The total count of buckets: 7 Bucket 0: empty Bucket 1: {15, 150}, Bucket 2: {30, 300}, Bucket 3: {10, 100}, {10, 100}, Bucket 4: empty Bucket 5: empty Bucket 6: {20, 200},

Program 2:

CPP `

// C++ program to illustrate the // unordered_multimap::bucket_count() #include <bits/stdc++.h> using namespace std;

int main() {

// declaration
unordered_multimap<char, char> sample;

// inserts key and element
sample.insert({ 'a', 'b' });
sample.insert({ 'a', 'b' });
sample.insert({ 'b', 'c' });
sample.insert({ 'r', 'a' });
sample.insert({ 'c', 'b' });

cout << "The total count of buckets: " 
     << sample.bucket_count();

// prints all element bucket wise
for (int i = 0; i < sample.bucket_count(); i++) {

    cout << "\nBucket " << i << ": ";

    // if bucket is empty
    if (sample.bucket_size(i) == 0)
        cout << "empty";

    for (auto it = sample.cbegin(i); 
                it != sample.cend(i); it++)
        cout << "{" << it->first << ", " 
             << it->second << "}, ";
}
return 0;

}

`

Output:

The total count of buckets: 7 Bucket 0: {b, c}, Bucket 1: {c, b}, Bucket 2: {r, a}, Bucket 3: empty Bucket 4: empty Bucket 5: empty Bucket 6: {a, b}, {a, b},