Subtracts one iterator from another and returns the difference.
template<class RandomIterator1, class RandomIterator2>
Tdiff operator-(
const move_iterator<RandomIterator1>& _Left,
const move_iterator<RandomIterator2>& _Right
);
template<class RandomIterator1, class RandomIterator2>
Tdiff operator-(
const reverse_iterator<RandomIterator1>& _Left,
const reverse_iterator<RandomIterator2>& _Right
);
Parameters
_Left
An iterator._Right
An iterator.
Return Value
The difference between two iterators.
Remarks
The first template operator returns _Left.base() - _Right.base().
The second template operator returns _Right.current - _Left.current.
Tdiff is determined by the type of the returned expression. Otherwise, it is RandomIterator1::difference_type.
Example
// iterator_op_sub.cpp
// compile with: /EHsc
#include <iterator>
#include <vector>
#include <iostream>
int main( )
{
using namespace std;
int i;
vector<int> vec;
for (i = 0 ; i < 6 ; ++i )
{
vec.push_back ( 2 * i );
}
vector <int>::iterator vIter;
cout << "The initial vector vec is: ( ";
for ( vIter = vec.begin( ) ; vIter != vec.end( ); vIter++)
cout << *vIter << " ";
cout << ")." << endl;
vector <int>::reverse_iterator rVPOS1 = vec.rbegin ( ),
rVPOS2 = vec.rbegin ( );
cout << "The iterators rVPOS1 & rVPOS2 initially point to "
<< "the first element\n in the reversed sequence: "
<< *rVPOS1 << "." << endl;
for (i = 1; i < 5; ++i)
{
rVPOS2++;
}
cout << "The iterator rVPOS2 now points to the fifth "
<< "element\n in the reversed sequence: "
<< *rVPOS2 << "." << endl;
vector<int>::difference_type diff = rVPOS2 - rVPOS1;
cout << "The difference: rVPOS2 - rVPOS1= "
<< diff << "." << endl;
}
The initial vector vec is: ( 0 2 4 6 8 10 ). The iterators rVPOS1 & rVPOS2 initially point to the first element in the reversed sequence: 10. The iterator rVPOS2 now points to the fifth element in the reversed sequence: 2. The difference: rVPOS2 - rVPOS1= 4.
Requirements
Header: <iterator>
Namespace: std