C++ Array::rbegin() Function

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The C++ std::array::rbegin() function is used to return the reverse iterator pointing to the last element of the array, enabling reverse iteration. This iterator starts from the last element and moves towards the first element.

Syntax

Following is the syntax for std::array::rbegin() function.

reverse_iterator rbegin() noexcept;
const_reverse_iterator rbegin() const noexcept;

Parameters

It does not accepts any parameter.

Return Value

This function return a reverse iterator which points to the last element of the array.

Exceptions

This function never throws exception.

Time complexity

Constant i.e. O(1)

Example 1

In the following example, we are going to consider the basic usage of the rbegin() function.

#include <iostream>
#include <array>
int main() {
   std::array < int, 5 > a = {11,22,32,34,12};
   auto x = a.rbegin();
   std::cout << "Result : " << * x << std::endl;
   return 0;
}

Output

Output of the above code is as follows −

Result : 12

Example 2

Consider the following example, where we re going to use the rbegin() function in loop.

#include <iostream>
#include <array>
int main() {
   std::array < int, 5 > x = {12,23,34,45,56};
   std::cout << " ";
   for (auto a = x.rbegin(); a != x.rend(); ++a) {
      std::cout << * a << " ";
   }
   std::cout << std::endl;
   return 0;
}

Output

Following is the output of the above code −

56 45 34 23 12 

Example 3

Let's look at the following example, where we are going to modify the element using rbegin() function.

#include <iostream>
#include <array>
int main() {
   std::array < int, 4 > x = {1,3,4,5};
   * x.rbegin() = 2;
   std::cout << "Result : ";
   for (int a: x) {
      std::cout << a << " ";
   }
   std::cout << std::endl;
   return 0;
}

Output

If we run the above code it will generate the following output −

Result : 1 3 4 2