Method operator-

src/prevector.h:117–117

        const_iterator operator++(int) { const_iterator copy(*this); ++(*this); return copy; }
        const_iterator operator--(int) { const_iterator copy(*this); --(*this); return copy; }
        difference_type friend operator-(const_iterator a, const_iterator b) { return (&(*a) - &(*b)); }
        const_iterator operator+(size_type n) { return const_iterator(ptr + n); }
        const_iterator& operator+=(size_type n) { ptr += n; return *this; }
        const_iterator operator-(size_type n) { return const_iterator(ptr - n); }