assignment operator overloading in c++

Question

I have used the following code for assignment operator overloading:

SimpleCircle SimpleCircle::operator=(const SimpleCircle & rhs)
{
     if(this == &rhs         


        

Answer 1

The second is pretty standard. You often prefer to return a reference from an assignment operator so that statements like a = b = c; resolve as expected. I can't think of any cases where I would want to return a copy from assignment.

One thing to note is that if you aren't needing a deep copy it's sometimes considered best to use the implicit copy constructor and assignment operator generated by the compiler than roll your own. Really up to you though ...

Edit:

Here's some basic calls:

SimpleCircle x; // default constructor
SimpleCircle y(x); // copy constructor
x = y; // assignment operator

Now say we had the first version of your assignment operator:

SimpleCircle SimpleCircle::operator=(const SimpleCircle & rhs)
{
     if(this == &rhs)
        return *this; // calls copy constructor SimpleCircle(*this)
     itsRadius = rhs.getRadius(); // copy member
     return *this; // calls copy constructor
}

It calls the copy constructor and passes a reference to this in order to construct the copy to be returned. Now in the second example we avoid the copy by just returning a reference to this

SimpleCircle & SimpleCircle::operator=(const SimpleCircle & rhs)
{
    if(this == &rhs)
       return *this; // return reference to this (no copy)
    itsRadius = rhs.getRadius(); // copy member
    return *this; // return reference to this (no copy)
}