c++ overload operator==

Question

I have a class with the following

bool DistinctWord::operator==(const DistinctWord W) const
{
    return strWord == W.strWord;
}
bool DistinctWord::operator==(const DistinctWord& W) const 
{
    return strWord == W.strWord;
}

I'm doing this in my program

    DistinctWord* wordOne = new DistinctWord("Test");
    DistinctWord* wordTwo = new DistinctWord("Test");

    if(*wordOne == *wordTwo)
        cout << "true";
    else
        cout << "false";

I get this error

error C2678: binary '==' : no operator found which takes a left-hand operand of type 'DistinctWord' (or there is no acceptable conversion) could be 'built-in C++ operator==(DistinctWord *, DistinctWord *

)'

I'm probably just not understanding the right way to overload.

Sorry for the simple question. TIA

Answer 1

EDIT:

OK, I've figured out your problem. It is the non-reference version of the operator== . It makes the operator== ambiguous. Simply remove it (as I originally suggested) and it'll work fine.

---

EDIT:

In response to your edit, you should still remove the first version of the operator== There is no need to make a copy of the object in question and then compare it. The second operator== looks reasonable and should work. Is there anything else you are leaving out?

---

EDIT:

The following compiles just fine for me using g++ 4.4.1:

#include <iostream>

struct DistinctWord {
    DistinctWord(const std::string &s) : strWord(s){}

    bool operator==(const DistinctWord& W) const {
        return strWord == W.strWord;
    }

    std::string strWord;
};


int main() {
    DistinctWord* wordOne = new DistinctWord("Test");
    DistinctWord* wordTwo = new DistinctWord("Test");

    if(*wordOne == *wordTwo)
        std::cout << "true";
    else
        std::cout << "false";
}

If you are still having problems, then you are not showing all relevant code...

---

First of all, where is the definition for DistinctWord and how does it relate to Word ?

Beyond that, you should do this:

bool Word::operator==(const Word& W) const {
     return strWord == W.strWord;
}

and just remove the two operator== 's you currently have. The first is making a copy then comparing which is silly, and your second is comparing a modifiable reference and always returning true which doesn't really serve any purpose.

This one should work fine.