lst-0448-book.cpp
auto operator<=>(const Adresse& re) const {
array a{strasse, plz, ort};
array b{re.strasse, re.plz, re.ort};
return lexicographical_compare_three_way(begin(a), end(a), begin(b), end(b));
}
auto operator<=>(const Adresse& re) const {
array a{strasse, plz, ort};
array b{re.strasse, re.plz, re.ort};
return lexicographical_compare_three_way(begin(a), end(a), begin(b), end(b));
}