static_cast Confusion

[paulcrown]

Greetings,

I can not seem to get my brain wrapped around static_cast. Can you help me understand what is wrong in ANY of my following three examples:

class RSet 
{
	public:
		int Test();
}

class DSet : RSet
{
}


DSet MyFirst()
{
	RSet goodval;
	goodval = GetValue();
	cout << goodval.Test();					// 3

	DSet badval;
	badval = static_cast<DSet&>(goodval);
	cout << badval.Test();					// 0
	
	return badval;
} 

DSet MySecond()
{
	RSet goodval;
	goodval = GetValue();
	cout << goodval.Test();					// 3

	Rset* rcopy = new DSet();
	rcopy = &goodval;
	
	DSet* dcopy = static_cast<DSet*>(rcopy);
        DSet fcopy = *dcopy;
        cout << fcopy.Test();					// 0
    
        return fcopy;
}

DSet MyThird()
{
	DSet badval;
	RSet& goodval = badval;
	
	RSet goodval;
	goodval = GetValue();
	cout << goodval.Test();					// 3
	
	DSet* dcopy = static_cast<DSet&>(goodval);
	cout << dcopy.Test();					// 0
	
        return dcopy;
}

In both cases Test() should be equal to 3, but my cast statements don't pass the same value.

Thanks in advance.

[Cubbi]

That doesn't compile. But if the pseudocode in the beginning is any indication, DSet is derived from RSet, so accessing an RSet object through a reference to DSet is undefined.