Why is there a difference when overloading different operators?

Question

Consider the following code snippet:

class Complex {
    double real, im;
    public:
    Complex(double real, double im) {
        this->real = real;
        this->im = im;
    } 
    Complex operator + (Complex const& sec) {
        Complex ret(real + sec.real, im + sec.im);
        return ret;
    }
    friend ostream& operator<<(ostream& os, const Complex& com);
};

ostream& operator << (ostream& os, const Complex& com) {
    os << com.real << " " << com.im << "i";
    return os;
}

Why doesn't the operator overloading of + have to be declared as friend as it will also want to access the private variables of the class from outside, similar to when overloading the << operator? At least that's what I thought but apparently this is not the case.

since a lot of ppl think that they know everything here is a good link for you. https://www.learncpp.com/cpp-tutorial/overloading-the-io-operators/ — , Mar 20 '21 at 23:50
There was an article explaining why `operator<>>` were implemented this way but I cannot find it, and why they cannot be members of your class. — , Mar 20 '21 at 23:54
and pls read this: https://stackoverflow.com/questions/4421706/what-are-the-basic-rules-and-idioms-for-operator-overloading/4421729#4421729. As I said in an answer LHO (object that you are modifying) has to be of your own class. — , Mar 21 '21 at 00:10
Does this answer your question? [What are the basic rules and idioms for operator overloading?](https://stackoverflow.com/questions/4421706/what-are-the-basic-rules-and-idioms-for-operator-overloading) — , Mar 21 '21 at 00:11

score 3 · Answer 1 · answered Mar 20 '21 at 23:27

3

A member function can access all the variables of a class, public or private. You only need friend for functions or classes that aren't part of your class.

answered Mar 20 '21 at 23:27

Mark Ransom

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so I could also write the overloading of the `< – Hilberto1 Mar 20 '21 at 23:29
1

@Descrates — yes, but … you can’t write it as a member function because its first argument is an `ostream&`, not a `Complex`. – Pete Becker Mar 20 '21 at 23:31
1

@Descrates no you can't, because the syntax of `< – Mark Ransom Mar 20 '21 at 23:31
2

A [good book](https://stackoverflow.com/questions/388242/the-definitive-c-book-guide-and-list) is the best way to learn C++. – sweenish Mar 20 '21 at 23:37

Why is there a difference when overloading different operators?

1 Answers1