Different Ways to Insert Elements in Set in C++ STL

Last Updated : 03 Apr, 2023

Prerequisites:

Set in C++

The C++ Standard Template Library offers containers called Sets. It functions essentially in the same ways as a binary search tree and is used to store different elements in increasing/decreasing order.

There are different methods to insert elements in the set as mentioned below:

Adding one element to set
Inserting an Iterator Range into a Set
Inserting an Initializer List in the Set

1. Adding one element to set

The basic way to add an element is a set is to use an insert() function where the value of the element is passed as a parameter to this function.

Syntax:

set_name.insert(element)

C++

// C++ program for inserting // Elements In set // one by one #include <bits/stdc++.h> using namespace std;  int main() {     // Create an empty set     set<int> s;      // Adding values to the set     s.insert(10);     s.insert(20);     s.insert(30);      // Printing the set     for (int x : s) {         cout << x << " ";     }      return 0; }

Output

10 20 30

Time Complexity : O(log n)
Auxiliary Space : O(n)

2. Inserting an Iterator Range into a Set

We can insert any other container elements into sets using iterators. In order to insert a range of elements from another container 2 parameters are required which are basically iterators pointing to starting and ending elements of that range.

Syntax:

set_name.insert(Iterator starting, Iterator ending);

C++

// C++ program to Insert // Elements In set using // Iterator Range #include <bits/stdc++.h> using namespace std;  int main() {     vector<int> v{ 10, 20, 30 };     // Create an empty set     set<int> s;      // Inserting values of vector to set     s.insert(v.begin(), v.end());      // Printing the set     for (int x : s) {         cout << x << " ";     }      return 0; }

Output

10 20 30

3. Inserting an Initializer List in Set

One more way to add the elements to a set is by inserting all elements from a list into the set. Given below is the syntax for this approach.

Syntax:

set_name.insert({element1,element2,element3,element4});

C++

// C++ program for inserting // Elements in set using // Initializer List #include <bits/stdc++.h> using namespace std;  int main() {     // Create an empty set     set<int> s;      // Inserting all elements of the list     // As we are inserting into set so the      // duplicate elements are rejected     // and only one occurrence is considered.     s.insert({10, 20, 30, 20, 10});          // Printing the set     for (int x : s)         cout << x << " ";      return 0; }