Question

So the code in question is this:

const String String::operator+ (const String& rhs)  
{  
    String tmp;  
    tmp.Set(this->mString);  
    tmp.Append(rhs.mString);  
    return tmp;  
}  

This of course places the String on the stack and it gets removed and returns garbage.
And placing it on the heap would leak memory. So how should I do this?

Answer 1

Your solution doesn’t return garbage if you have a working copy constructor – the String object tmp is copied into the result object before it is destroyed at the end of the block.

You could do this better by replacing

String tmp;
tmp.Set(this->mString);

with

String tmp(*this);

(you need a correctly working copy constructor for this, but you need it anyways for your return statement)