C++ Deque crbegin

C++ Deque crbegin function returns a constant reverse iterator referring to the last element of the deque. An iterator can be incremented or decremented but it cannot modify the content of deque.

Where , crbegin stands for constant reverse beginning.

Syntax

const_reverse_iterator crbegin();

Parameter

It does not contain any parameter.

Return value

It returns a constant reverse iterator pointing to the last element in the deque container.

Example 1

Let's see a simple example

#include <iostream>
#include<deque>
using namespace std;
int main()
{
   deque<int> i={10,20,30,40,50};
   deque<int>::const_reverse_iterator citr;
   for(citr=i.crbegin();citr!=i.crend();++citr)
   {
       cout<<*citr;
       cout<<" ";
   }
   return 0;}

Output:

50 40 30 20 10

In this example, crbegin function is used to return an iterator of the last element and for loop is iterated till it reaches the first element of the deque.

Example 2

Let's see a simple example when iterator is incremented.

#include <iostream>
#include<deque>
using namespace std;
int main()
{
   deque<string> fruit={"electronics","computer science","mechanical","electrical"};
   deque<string>::const_reverse_iterator citr=fruit.crbegin()+1;
  cout<<*citr;
   return 0;
}

Output:

mechanical

In this example, constant reverse iterator is incremented by one. Therefore, it access the second element from backwards.