Operator overloading in C++

Question

I have the following constructor in my "fraction class"

fraction::fraction(int num, int den=1)
{
     numerator=num;
     denominator=den;
}

I also have a function called lcm() that returns the least common multiple of values given as parameters. I need to overload the "+" operator in the class fraction. The operator "+" is to add two rational values.

Questions:

1. Write the overloaded "+" operator as a member method of the class.
2. Write the overloaded "+" operator as a friend function to the class.
3. One of these gives an advantage over the other. Which one is better? Why is it better?

Any help will be greatly appreciated.

Answer 1

Standard algorithms. Study. Do you really expect people to do your homework? Google is your friend.

Answer 2

Have a look at: SO: How to define a friend function and how to do operator overloading?

1. Friends in C++
2. Operator overloading in C++

Also, while homework is allowed, you'll get better answers if you ask specific questions about what things you are actually confused on.

You aren't going to get a good response if you just list off homework problems and expect us to do them for you.

For example, attempt your homework yourself and if you hit a snag, post a specific question citing your attempt, what isn't working and we'll help tell you why.

Answer 3

Some ideas which are possibly not so easy to find using google, so i will tell you:

The friend, non-member function is better. It will allow conversions on both left and right operand of the + operator. The + operator is symmetric, and the non-member operator function supports this property syntactically by treating each side of the operator the same way.

On another side, you can write that implementing the operator as a non-friend, non-member function is even better, because then you have one function less that has access to implementation details of the class. But as this is not what was asked for, i would put it as a side-node, if at all.

I will leave writing the code to you, though. Just the general idea is that you write the function somewhat like this:

fraction operator+(fraction const& left, fraction const& right) {
    // put your code here...
}

As to how you declare that function as friend - i think there are many sites on the internet explaining that in great detail (have a look into the FAQ Simucal linked to. It's really good). I wish you good luck :)