Partager via


deque::rbegin

Returns an iterator to the first element in a reversed deque.

const_reverse_iterator rbegin( ) const; 
reverse_iterator rbegin( );

Return Value

A reverse random-access iterator addressing the first element in a reversed deque or addressing what had been the last element in the unreversed deque.

Remarks

rbegin is used with a reversed deque just as begin is used with a deque.

If the return value of rbegin is assigned to a const_reverse_iterator, the deque object cannot be modified. If the return value of rbegin is assigned to a reverse_iterator, the deque object can be modified.

rbegin can be used to iterate through a deque backwards.

Example

// deque_rbegin.cpp
// compile with: /EHsc
#include <deque>
#include <iostream>

int main( ) 
{
   using namespace std;
   deque <int> c1;
   deque <int>::iterator c1_Iter;
   deque <int>::reverse_iterator c1_rIter;

   // If the following line had replaced the line above, an error 
   // would have resulted in the line modifying an element 
   // (commented below) because the iterator would have been const
   // deque <int>::const_reverse_iterator c1_rIter;
   
   c1.push_back( 10 );
   c1.push_back( 20 );
   c1.push_back( 30 );

   c1_rIter = c1.rbegin( );
   cout << "Last element in the deque is " << *c1_rIter << "." << endl;

   cout << "The deque contains the elements: ";
   for ( c1_Iter = c1.begin( ); c1_Iter != c1.end( ); c1_Iter++ )
      cout << *c1_Iter << " ";
   cout << "in that order.";
   cout << endl;

   // rbegin can be used to iterate through a deque in reverse order
   cout << "The reversed deque is: ";
   for ( c1_rIter = c1.rbegin( ); c1_rIter != c1.rend( ); c1_rIter++ )
      cout << *c1_rIter << " ";
   cout << endl;

   c1_rIter = c1.rbegin( );
   *c1_rIter = 40;  // This would have caused an error if a 
                    // const_reverse iterator had been declared as 
                    // noted above
   cout << "Last element in deque is now " << *c1_rIter << "." << endl;
}

Output

Last element in the deque is 30.
The deque contains the elements: 10 20 30 in that order.
The reversed deque is: 30 20 10 
Last element in deque is now 40.

Requirements

Header: <deque>

Namespace: std

See Also

Concepts

deque Class

deque Class Members

deque::rbegin and deque::rend

Standard Template Library