Thread: difference between returning a 'int&' instead of a 'int'

can someone tell me the difference, pros and cons of both the following functions.

Code:

class Node
{
	int data_;
	Node* prev_;
	Node* next_;
	
	public:
		Node(){data_ = 5;}
		~Node(){};
		int getdata(){return data_;}
};

int main()
{
	Node obj;
	cout << obj.getdata() << endl;
	return 0;
}

Code:

class Node
{
	int data_;
	Node* prev_;
	Node* next_;
	
	public:
		Node(){data_ = 5;}
		~Node(){};
		int& getdata(){return data_;}
};

int main()
{
	Node obj;
	cout << obj.getdata() << endl;
	return 0;
}

incase you didn't see it i added a '&' in front of the getdata member function.

well put Fillyourbrain.. thnks

An advantage of returning by reference is that you can cascade operations and that you can write directly to the data member (instead of using a 'set' function), e.g.

Code:

int main()
{
	Node obj1;
	Node obj2;
	Node obj3;
	
        obj1.getdata() = obj2.getdata() + obj3.getdata()
}

Is that to say that code like

Example:

Code:

static int global_x = 0;
static int global_y = 0;

int &setXY(int y)
{
  global_y = y;
  return global_x;
}

int main(void)
{
  setXY(5) = 3;
}

Is not sensible? Because I think its perfectly easy to follow.

--Truly I hope any new programmer takes me completely unseriously and never, ever considers writing anything as malformed as that.

From a library-user point of view? It's because you know the code.

Let's say you program a matrix class, then your clients will use C = A + B*D instead of some function nesting...

C = A + B*D is not analogous to setXY(3) = 5.