double Sale::savings(const Sale& other) const
{
return (bill() - other.bill());
}
bool operator <(const Sale& first, const Sale& second)
{
// Because of polymorphism, will correctly apply subclass method
// bill() instead of superclass method if subclass method implemented.
return (first.bill() < second.bill());
}
bool operator <(const Sale& first, const Sale& second) {
return (first.bill() < second.bill());
}