reverse_iterator::operator-=

Subtracts a specified offset from a reverse_iterator.

reverse_iterator<RandomIterator>& operator-=(
   difference_type _Off
);

Parameters

• _Off
  The offset to be subtracted from the reverse_iterator.

Remarks

This member function may only be used if the reverse_iterator satisfies the requirements for a random-access iterator.

The operator evaluates current + _Off. then returns *this.

Example

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

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

   vector<int> vec;
   for (i = 1 ; i < 6 ; ++i )
   {
      vec.push_back ( 3 * 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;

   // Initializing reverse_iterators to the first element
   vector <int>::reverse_iterator rVPOS1 = vec.rend ( ) - 1;
   
   cout << "The iterator rVPOS1 initially points to the last "
        << "element\n in the reversed sequence: "
        << *rVPOS1 << "." << endl;

   rVPOS1-=2;      // Subtraction of an offset
   cout << "After the -2 offset, the iterator rVPOS1 now points\n"
        << " to the 2nd element from the last in the reversed sequence: "
        << *rVPOS1 << "." << endl;
}

The vector vec is: ( 3 6 9 12 15 ). The vector vec reversed is: ( 15 12 9 6 3 ). The iterator rVPOS1 initially points to the last element in the reversed sequence: 3. After the -2 offset, the iterator rVPOS1 now points to the 2nd element from the last in the reversed sequence: 9.

Requirements

Header: <iterator>

Namespace: std

See Also

Reference

reverse_iterator Class

Standard Template Library

Other Resources

reverse_iterator Members