map rbegin() function in C++ STL

The rbegin() is a function in C++ STL. It returns a reverse iterator which points to the last element of the map. The reverse iterator iterates in reverse order and incrementing it means moving towards beginning of map.

SYNTAX:

r_i rbegin();
const_r_i rbegin() const;

Parameters:
It does not except any parameters.

Return Value: This method throws a reverse iterator to the reverse beginning of the sequence container.

Time Complexity:

O(1)

Example:

#include <iostream>
#include <map>
using namespace std;

int main()
{

    map<char, int> mp = {
        { 'a', 1 },
        { 'b', 2 },
        { 'c', 3 },
        { 'd', 4 },
        { 'e', 5 },
    };

    cout << "Map contains "
         << "following elements in"
         << " reverse order"
         << endl;

    for (auto i = mp.rbegin(); i != mp.rend(); ++i) {

        cout << i->first
             << " = "
             << i->second
             << endl;
    }

    return 0;
}

Output:

Map contains following elements in reverse order
e = 5
d = 4
c = 3
b = 2
a = 1

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