use set to get duplicates in c++

To use a set in C++ to get duplicates, follow these steps:

  1. Include the necessary header file: Begin by including the <set> header file, which provides the necessary functions and data structures for working with sets.

  2. Declare a set: Declare a set object of the desired type. For example, if you want to store integers, you can declare a set of type std::set<int> mySet;.

  3. Insert elements: Use the insert function to add elements to the set. For example, to add the integer 5 to the set, use mySet.insert(5);. You can repeat this step to insert multiple elements into the set.

  4. Check for duplicates: After inserting all the elements, you can check for duplicates by comparing the size of the set to the number of elements you inserted. If the size of the set is less than the number of elements, it means there are duplicates present.

  5. Retrieve duplicates: If duplicates are present, you can retrieve them by iterating over the set and checking the count of each element using the count function. If the count is greater than 1, it means the element is a duplicate.

Here's an example that demonstrates these steps:

#include <iostream>
#include <set>

int main() {
    std::set<int> mySet;

    mySet.insert(5); // Duplicate

    if (mySet.size() < 4) {
        std::cout << "Duplicates found!" << std::endl;

        for (const auto& element : mySet) {
            if (mySet.count(element) > 1) {
                std::cout << "Duplicate element: " << element << std::endl;
    } else {
        std::cout << "No duplicates found." << std::endl;

    return 0;

In this example, the set mySet contains four elements, but the size of the set is only 3, indicating the presence of duplicates. The program then iterates over the set and checks the count of each element. Since the count of 5 is greater than 1, it is identified as a duplicate and printed to the console.