24 Iterators library [iterators]

24.5 Iterator adaptors [predef.iterators]

24.5.1 Reverse iterators [reverse.iterators]

24.5.1.3 reverse_iterator operations [reverse.iter.ops]

24.5.1.3.12 operator[] [reverse.iter.opindex]

unspecified operator[]( typename reverse_iterator<Iterator>::difference_type n) const;

Returns: current[-n-1].