I am trying to construct a set of objects called guests. For this purpose, I overloaded the less than operator. The problem is that I'm not getting unique elements. I can't figure out why. The size of the set is always 2 in the following example.
// Online C compiler to run C program online
#include <iostream>
#include <set>
#include <string>
class Guest{
public:
Guest(const std::string &fn, const std::string &ln, const std::string &em, const std::string &loy):firstname(fn), lastname(ln), email(em),loyalty(loy){}
std::string firstname;
std::string lastname;
std::string email;
std::string loyalty;
};
bool operator<(const Guest& l, const Guest& r){
return (l.firstname < r.firstname) or ((l.firstname == r.firstname) and
((l.lastname < r.lastname) or ((l.lastname == r.lastname) and
((l.email < r.email) or ((l.email == r.email) and
((l.loyalty < r.loyalty) or ((l.loyalty == r.loyalty))))))));
}
int main() {
Guest g1("g1","g2","g3","g4");
Guest g2("g1","g2","g3","g4");
std::set<Guest> guests = {g1,g2};
std::cout << guests.size() << std::endl; //Size is always 2 in here. It should be 1
return 0;
}
CodePudding user response:
You should remove the last part or ((l.loyalty == r.loyalty))
, otherwise the operator<
would return true
when all the data members of Guest
are equivalent.
bool operator<(const Guest& l, const Guest& r){
return (l.firstname < r.firstname) or ((l.firstname == r.firstname) and
((l.lastname < r.lastname) or ((l.lastname == r.lastname) and
((l.email < r.email) or ((l.email == r.email) and
((l.loyalty < r.loyalty) ))))));
}
Or make it much simpler with std::tie
.
bool operator<(const Guest& l, const Guest& r){
return std::tie(l.firstname, l.lastname, l.email, l.loyalty) <
std::tie(r.firstname, r.lastname, r.email, r.loyalty);
}