Method operator-

src/prevector.h:66–66

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