unordered_multiset equal_range() function in C++STL

Last Updated : 02 Aug, 2018

The unordered_multiset::equal_range() is a built-in function in C++ STL which returns the range in which all the elements are equal to a given value. It returns a pair of iterators where the first is an iterator pointing to the lower bound of the range and second is an iterator pointing to the upper bound of the range. If there is no element equal to a given value in the container, then it returns a pair where both lower and upper bound points to the position after the end of the container. Syntax:

unordered_multiset_name.equal_range(value)

Parameters: The function accepts an element val whose range is to be returned. Return Value: It returns a pair of iterators. Below programs illustrates the above function: Program 1:

CPP

// C++ program to illustrate the // unordered_multiset::equal_range() function #include <bits/stdc++.h> using namespace std; int main() {  // declaration  unordered_multiset<int> sample;  // inserts element  sample.insert(100);  sample.insert(100);  sample.insert(100);  sample.insert(200);  sample.insert(500);  sample.insert(500);  sample.insert(600);  // iterator of pairs pointing to range  // which includes 500 and print by iterating in range  auto itr = sample.equal_range(500);  for (auto it = itr.first; it != itr.second; it++) {  cout << *it << " ";  }  cout << endl;  // iterator of pairs pointing to range  // which includes 100 and print by iterating in range  itr = sample.equal_range(100);  for (auto it = itr.first; it != itr.second; it++) {  cout << *it << " ";  }  return 0; }

Output:

 500 500 100 100 100

Program 2:

CPP

// C++ program to illustrate the // unordered_multiset::equal_range() function #include <bits/stdc++.h> using namespace std; int main() {  // declaration  unordered_multiset<char> sample;  // inserts element  sample.insert('a');  sample.insert('a');  sample.insert('b');  sample.insert('c');  sample.insert('d');  sample.insert('d');  sample.insert('d');  // iterator of pairs pointing to range  // which includes 'a' and print by iterating in range  auto itr = sample.equal_range('a');  for (auto it = itr.first; it != itr.second; it++) {  cout << *it << " ";  }  cout << endl;  // iterator of pairs pointing to range  // which includes 'd' and print by iterating in range  itr = sample.equal_range('d');  for (auto it = itr.first; it != itr.second; it++) {  cout << *it << " ";  }  return 0; }