Insertion and Deletion in STL Set C++ program

In this tutorial, we will be discussing a program to understand the insertion and deletion in STL set in C++.

The set is a container element. The properties that make it unique is that it can only contain unique elements and they can be looped over in a sorted manner.

Example

Insertion

 Live Demo

#include<iostream> #include<set> using namespace std; int main(){    set<int> st;    //declaring iterators    set<int>::iterator it = st.begin();    set<int>::iterator it1, it2;    pair< set<int>::iterator,bool> ptr;    //inserting a single element    ptr = st.insert(20);    if (ptr.second)       cout << "The element was newly inserted" ;    else cout << "The element was already present" ;       cout << "\nThe set elements after 1st insertion are : ";    for (it1 = st.begin(); it1!=st.end(); ++it1)       cout << *it1 << " ";    st.insert(it, 24);    cout << "\nThe set elements after 2nd insertion are : ";    for (it1 = st.begin(); it1!=st.end(); ++it1)       cout << *it1 << " ";    int arr[3] = { 25, 24, 26 };    st.insert(arr, arr+3);    cout << "\nThe set elements after 3rd insertion are : ";    for (it1 = st.begin(); it1!=st.end(); ++it1)       cout << *it1 << " "; }

Output

The element was newly inserted The set elements after 1st insertion are : 20 The set elements after 2nd insertion are : 20 24 The set elements after 3rd insertion are : 20 24 25 26

Deletion

 Live Demo

#include<iostream> #include<set> using namespace std; int main(){    set<int> st;    //declaring iterators    set<int>::iterator it;    set<int>::iterator it1;    set<int>::iterator it2;    pair< set<int>::iterator,bool> ptr;    //inserting values in set    for (int i=1; i<10; i++)       st.insert(i*5);    cout << "The set elements after insertion are : ";    for (it1 = st.begin(); it1!=st.end(); ++it1)       cout << *it1 << " ";    it = st.begin();    cout << endl;    ++it;    st.erase(it);    //printing set elements after deletion    cout << "The set elements after 1st deletion are : ";    for (it1 = st.begin(); it1!=st.end(); ++it1)       cout << *it1 << " ";    st.erase(40);    cout << "\nThe set elements after 2nd deletion are : ";    for (it1 = st.begin(); it1!=st.end(); ++it1)       cout << *it1 << " ";    ++it;    ++it;    ++it;    ++it;    st.erase(it, st.end());    cout << "\nThe set elements after 3rd deletion are : ";    for (it1 = st.begin(); it1!=st.end(); ++it1)       cout << *it1 << " ";    cout << endl; }

Output

The set elements after insertion are : 5 10 15 20 25 30 35 40 45 The set elements after 1st deletion are : 5 15 20 25 30 35 40 45 The set elements after 2nd deletion are : 5 15 20 25 30 35 45 The set elements after 3rd deletion are : 5 15 20