CODEWITHSUNDEEP
c++pointersoverloadingstructureoperator-keyword
Lucas
Lucas

Reputation: 367

C++ overloading single operator passing 2 structures as pointers

Ok. I have the structure:

struct birthdayPerson
{
    int day, month, year;
    public:
        void Show()
        {
            std::cout << day << " " << month << " " << year << std::endl;
        }
};

Then i want to overload the "==" so it can compare 2 instateated structs if those people has the same birthday (day and month). I have a 2 element array pointer of this struct:

birthdayPerson * personBirth[2];
personBirth[0] = new birthdayPerson;
personBirth[1] = new birthdayPerson;

Then i overload like this:

bool operator==(birthdayPerson person1, birthdayPerson person2)
{
    return (person1.day == person2.day &&
    person1.month == person2.month);
}

And finally i use in the code:

bool sameBirthDay = personBirth[0] == personBirth[1];

But, why it doesn't call the "overladed" function (operator)?. What am i doing worong?

Upvotes: 0

Views: 58

Answers (3)

cigien
cigien

Reputation: 60238

personBirth is an array of BirthdayPerson*. You need to dereference pointers to compare the objects they are pointing to:

bool sameBirthDay = *personBirth[0] == *personBirth[1];

Otherwise you are comparing 2 pointers, which is not the same thing. (and also the reason it doesn't call your operator== on birthdayPerson).

Also, I can't see any reason why you are using pointers at all in this code. You could just create objects instead. If you want a collection of objects, use std::vector, or if you know the number of objects you need at compile time, you can use std::array.

This is not related to your question, but as @RemyLebeau points out in their answer, your operator== is not idiomatic. The signature should instead be:

bool operator==(birthdayPerson const &person1, birthdayPerson const &person2);

Otherwise you are making needless copies of the objects you're comparing.

Upvotes: 3

Remy Lebeau
Remy Lebeau

Reputation: 597036

First off, your operator== should take its parameters by const reference:

bool operator==(const birthdayPerson &person1, const birthdayPerson &person2)

Second, your array contains birthdayPerson* pointers, not actual birthdayPerson objects. Your statement personBirth[0] == personBirth[1] is comparing pointers, which is why your operator is not invoked. You need to deference the pointers to compare the objects properly:

bool sameBirthDay = *(personBirth[0]) == *(personBirth[1]);

Otherwise, change the array to hold objects, rather than pointers to objects:

birthdayPerson personBirth[2];
...
bool sameBirthDay = personBirth[0] == personBirth[1];

Upvotes: 4

sariug
sariug

Reputation: 106

Do you initiate them ? If not it fails. You do not have a default value.

bool operator==(birthdayPerson person1, birthdayPerson person2)
{
    std:: cout << person1.day <<" "<<person2.day<<"\n";
    return (person1.day == person2.day &&
    person1.month == person2.month);
}

if no initiated:

4196144 32766

If you compare the pointers, you dont call the overloaded function. Comparing the addresses. Again fail.

Upvotes: -2

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