C++ multimap rbegin() function

The C++ multimap rbegin() function is used to return a reverse iterator referring to the last element of the multimap container.

A reverse iterator of multimap moves in reverse direction and incrementing it until it reaches to the beginning (First element) of the multimap container.

Syntax

Parameter

None

Return value

It returns a reverse iterator pointing to the last element of the multimap.

Complexity

Constant.

Iterator validity

No changes.

Data races

The container is accessed neither the const nor the non-const versions modify the container.

Exception safety

This function never throws exception.

Example 1

Let's see the simple example for rbegin() function:

Output:

c = 300
b = 200
a = 300
a = 100

In the above example, rbegin() function is used to return a reverse iterator pointing to the last element in the mymultimap multimap.

Because multimap stores the elements in sorted order of keys therefore, iterating over a multimap will result in above order i.e. sorted order of keys.

Example 2

Let's see a simple example to iterate over the multimap in reverse order using while loop:

Output:

ddd :: 11
ccc :: 13
ccc :: 12
aaa :: 10

In the above example, we are using while loop to iterate over the multimap in reverse order and rbegin() function initializing the last element of the multimap.

Because multimap stores the elements in sorted order of keys therefore, iterating over a multimap will result in above order i.e. sorted order of keys.

Example 3

Let's see a simple example to get the first element of the reversed multimap:

Output:

The first element of the reversed multimap m1 is: {4, 50}

In the above example, rbegin() function returns the first element of the reversed multimap m1 i.e. {4,50}.

Example 4

Let's see a simple example to sort and calculate the highest marks:

Output:

Marks | Roll Number
______________________
480   |  30
425   |  50
425   |  10
300   |  40
300   |  20
Highest Marks is: 480 
Roll Number of Topper is: 30

In the above example, a multimap marks is implemented where the Roll Number is being stored as value and marks as key. This enables us to take advantage of the auto sorting in multimaps and lets us to identify the Roll number of the element with the highest marks.