set::rbegin() and set::rend() in C++ STL

1. set::rbegin() is a built-in function in C++ STL which returns a reverse iterator pointing to the last element in the container.

   Syntax:

   reverse_iterator set_name.rbegin()
   

   Parameters: The function does not take any parameter.

   Return value: The function returns a reverse iterator pointing to the last element in the container.

   Program to demonstrate the set::rbegin() method:

   Program 1:

   // CPP program to demonstrate the
   // set::rbegin() function
   #include <bits/stdc++.h>
   using namespace std;
   int main()
   {
   
       int arr[] = { 14, 12, 15, 11, 10 };
   
       // initializes the set from an array
       set<int> s(arr, arr + 5);
   
       set<int>::reverse_iterator rit;
   
       // prints all elements in reverse order
       for (rit = s.rbegin(); rit != s.rend(); rit++)
           cout << *rit << " ";
   
       cout << "\nThe last element in set is " << *(s.rbegin());
   
       return 0;
   }
   Output:

   15 14 12 11 10 
   The last element in set is 15
   

2. set::rend() in an inbuilt function in C++ STL which returns a reverse iterator pointing to the theoretical element right before the first element in the set container.

   Syntax:

   reverse_iterator set_name.rend()
   

   Parameter: The function does not accepts any parameter.

   Return value: The function returns a reverse iterator pointing to the theoretical element right before the first element in the set container.

   Below programs illustrate the function:

   Program 1:

   // CPP program to demonstrate the
   // set::rend() function
   #include <bits/stdc++.h>
   using namespace std;
   int main()
   {
   
       int arr[] = { 4, 3, 5, 1, 2 };
   
       // initializes the set from an array
       set<int> s(arr, arr + 5);
   
       set<int>::reverse_iterator rit;
   
       // prints all elements in reverse order
       for (rit = s.rbegin(); rit != s.rend(); rit++)
           cout << *rit << " ";
   
       return 0;
   }
   Output:

   5 4 3 2 1