reverse_iterator::reverse_iterator

Article
07/29/2015

Constructs a default reverse_iterator or a reverse_iterator from an underlying iterator.

reverse_iterator( ); 
explicit reverse_iterator( 
   RandomIterator _Right 
); 
template<class Type> 
   reverse_iterator( 
      const reverse_iterator<Type>& _Right 
   );

Parameters

_Right
The iterator that is to be adapted to a reverse_iterator.

Return Value

A default reverse_iterator or a reverse_iterator adapting an underlying iterator.

Remarks

The identity which relates all reverse iterators to their underlying iterators is:

&*(reverse_iterator ( i ) ) == &*( i – 1 ).

In practice, this means that in the reversed sequence the reverse_iterator will refer to the element one position beyond (to the right of) the element that the iterator had referred to in the original sequence. So if an iterator addressed the element 6 in the sequence (2, 4, 6, 8), then the reverse_iterator will address the element 4 in the reversed sequence (8, 6, 4, 2).

Example

// reverse_iterator_reverse_iterator.cpp
// compile with: /EHsc
#include <iterator>
#include <algorithm>
#include <vector>
#include <iostream>

int main( )
{
   using namespace std;
   int i;

   vector<int> vec;
   for ( i = 1 ; i < 6 ; ++i )
   {
      vec.push_back ( i );
   }
   
   vector <int>::iterator vIter;
   cout << "The vector vec is: ( ";
   for ( vIter = vec.begin ( ) ; vIter != vec.end ( ); vIter++)
      cout << *vIter << " ";
   cout << ")." << endl;

   vector <int>::reverse_iterator rvIter;
   cout << "The vector vec reversed is: ( ";
   for ( rvIter = vec.rbegin( ) ; rvIter != vec.rend( ); rvIter++)
      cout << *rvIter << " ";
   cout << ")." << endl;

   vector <int>::iterator pos;
   pos = find ( vec.begin ( ), vec.end ( ), 4 );
   cout << "The iterator pos = " << *pos << "." << endl;

   vector <int>::reverse_iterator rpos ( pos );
   cout << "The reverse_iterator rpos = " << *rpos 
        << "." << endl;
}

Output

The vector vec is: ( 1 2 3 4 5 ).
The vector vec reversed is: ( 5 4 3 2 1 ).
The iterator pos = 4.
The reverse_iterator rpos = 3.

Requirements

Header: <iterator>

Namespace: std

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