operator-(std::reverse_iterator)
template< class Iterator >
typename reverse_iterator<Iterator>::difference_type
operator-( const reverse_iterator<Iterator>& lhs,
const reverse_iterator<Iterator>& rhs ); |
(until C++11) | |
template< class Iterator1, class Iterator2 >
auto operator-( const reverse_iterator<Iterator1>& lhs,
const reverse_iterator<Iterator2>& rhs
) -> decltype(rhs.base() - lhs.base()); |
(since C++11) (until C++17) |
|
template< class Iterator1, class Iterator2 >
constexpr auto operator-( const reverse_iterator<Iterator1>& lhs,
const reverse_iterator<Iterator2>& rhs
) -> decltype(rhs.base() - lhs.base()); |
(since C++17) |
Returns the distance between two iterator adaptors.
Parameters
| lhs, rhs | - | iterator adaptors to compute the difference of |
Return value
rhs.base() - lhs.base().
Example
#include <iostream>
#include <iterator>
#include <list>
#include <vector>
int main()
{
{
std::vector v {0, 1, 2, 3};
std::reverse_iterator<std::vector<int>::iterator>
ri1 { std::reverse_iterator{ v.rbegin() } },
ri2 { std::reverse_iterator{ v.rend() } };
std::cout << (ri2 - ri1) << ' '; // 4
std::cout << (ri1 - ri2) << '\n'; // -4
}
{
std::list l {5, 6, 7, 8};
std::reverse_iterator<std::list<int>::iterator>
ri1{ std::reverse_iterator{ l.rbegin() } },
ri2{ std::reverse_iterator{ l.rend() } };
// auto n = (ri1 - ri2); // error: the underlying iterators do not
// model the random access iterators
}
}
Output:
4 -4
See also
| advances or decrements the iterator (public member function) |
|
| advances the iterator (function template) |
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