unordered_multimap bucket() function in C++ STL Last Updated : 08 Aug, 2018 Summarize Comments Improve Suggest changes Share Like Article Like Report The unordered_multimap::bucket() is a built-in function in C++ STL which returns the bucket number in which a given key is. Bucket size varies from 0 to bucket_count-1. Syntax: unordered_multimap_name.bucket(key) Parameters: The function accepts a single mandatory parameter key which specifies the key whose bucket number is to be returned. Return Value: It returns an unsigned integral type which signifies the bucket number in which the key is. Below programs illustrates the above function: Program 1: CPP // C++ program to illustrate the // unordered_multimap::bucket() #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 }); // iterate for all elements and print its bucket number for (auto it = sample.begin(); it != sample.end(); it++) { cout << "The bucket number in which {" << it->first << ", " << it->second << "} is " << sample.bucket(it->first) << endl; } return 0; } Output: The bucket number in which {15, 150} is 1 The bucket number in which {30, 300} is 2 The bucket number in which {20, 200} is 6 The bucket number in which {10, 100} is 3 The bucket number in which {10, 100} is 3 Program 2: CPP // C++ program to illustrate the // unordered_multimap::bucket() #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' }); // iterate for all elements and print its bucket number for (auto it = sample.begin(); it != sample.end(); it++) { cout << "The bucket number in which {" << it->first << ", " << it->second << "} is " << sample.bucket(it->first) << endl; } return 0; } Output: The bucket number in which {c, b} is 1 The bucket number in which {r, a} is 2 The bucket number in which {b, c} is 0 The bucket number in which {a, b} is 6 The bucket number in which {a, b} is 6 Comment More infoAdvertise with us Next Article unordered_multimap empty() function in C++ STL G gopaldave Follow Improve Article Tags : Misc C++ STL CPP-Functions cpp-unordered_multimap +1 More Practice Tags : CPPMiscSTL Similar Reads Unordered Multimap in C++ STL In C++, the unordered_multimap is an unordered associative container that stores data in the form of key-value pairs. 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