deque rbegin() function in C++ STL

The deque::rbegin() is an inbuilt function in C++ STL which returns a reverse iterator which points to the last element of the deque (i.e., its reverse beginning). Syntax:

deque_name.rbegin()

Parameter: This function does not accept any parameters. Return value: It returns a reverse iterator which points to the last element of the deque. Below programs illustrates the above function: Program 1:

CPP

// C++ program to illustrate the
// deque::rbegin() function
#include <bits/stdc++.h>
using namespace std;

int main()
{
    deque<int> dq = { 10, 20, 30, 40, 50 };

    cout << "The deque in reverse order: ";

    // prints the elements in reverse order
    for (auto it = dq.rbegin(); it != dq.rend(); ++it)
        cout << *it << " ";

    return 0;
}

Output:

The deque in reverse order: 50 40 30 20 10

Time Complexity: O(n)

Auxiliary Space: O(n)

Program 2:

CPP

// C++ program to illustrate the
// deque::rbegin() function
#include <bits/stdc++.h>
using namespace std;

int main()
{
    deque<char> dq = { 'a', 'b', 'c', 'd', 'e' };

    cout << "The deque in reverse order: ";

    // prints the elements in reverse order
    for (auto it = dq.rbegin(); it != dq.rend(); ++it)
        cout << *it << " ";

    return 0;
}

Output:

The deque in reverse order: e d c b a

Time Complexity: O(n)

Auxiliary Space: O(n)