The std::map::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.
Returns: It returns a reverse iterator which points to the last element of the map.
Time Complexity: O(1)
Below examples illustrate the map::rbegin() method:
Example 1:
// C++ Program to illustrate // map::rbegin() method #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
Example 2:
// C++ Program to illustrate // map::rbegin() method #include <iostream> #include <map> using namespace std;
int main()
{ map< char , char > mp = {
{ 'a' , 'A' },
{ 'b' , 'B' },
{ 'c' , 'C' },
{ 'd' , 'D' },
{ 'e' , 'E' },
};
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 = E d = D c = C b = B a = A
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