unordered_multimap bucket_count() function in C++ STL

Last Updated : 08 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:

unordered_multimap_name.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},