Thread: Not able to access private data members

Hi. Can anyone tell me why I am not being allowed to access private data members when I use this friend function?

Code:

class Card
{
	public:
		Card();
		void setSuit(string newSuit);
        	friend istream& operator >> (istream& is, Card& cd);
	private:
		string mSuit;
		int mValue;
};

istream& operator >> (istream& is, Card& cd)
{
	is>>cd.mSuit>>cd.mValue;
	return is;
}

Thanks in advance.

Thanks. I did this (I tried what you said before, it didn't seem to work):

Code:

class Card
{
	public:
		Card();
		void setSuit(string newSuit);
                                friend istream& operator >> (istream& is, Card& cd);
		int getmValue();
		string getmSuit();
	private:
		string mSuit;
		int mValue;
};

istream& operator >> (istream& is, Card& cd)
{
	is>>cd.getmSuit()>>cd.getmValue();
	return is;
}

int Card::getmValue()
{
	return mValue;
}

string Card::getmSuit()
{
	return mSuit;
}

MSVC++ 6.0 gives the following error:

Code:

C:\CSCI135\Assignment7\May2.cpp(54) : error C2679: binary '>>' : no operator defined which takes a right-hand operand of type 'int' (or there is no acceptable conversion)

Thanks.

...also, my professor states that one should be able to access the private data members directly, since one is using the friend function, and should not have to use accessor functions. He asked which compiler I was using, and I replied "MSVC++ 6.0." Does this work on another compiler perhaps? Is he right, or must one always use accessor functions in this situation? Thanks, Steve

...Thanks for letting me know that you could compile it in .NET. My professor has the class using the dev_c compiler. That's a far cry from the .NET compiler isn't it?

What you posted initially should work. Dev-C++ (the GCC compiler) is very standards compliant, and from what I have heard, so is .NET. VC++6, on the other hand, is notorious for not being compliant with the standard, and that is probably your problem. I'd recommend downloading Dev-C++ to use.

Thanks. I am downloading Dev-C++ now.

Hi. I am now having a problem with this:

Code:

class Card
{
  public:
    friend ifstream& operator >>(ifstream& is, Card& cd);  
    friend ostream& operator <<(ostream& os, Card cd);
  private:
    string mSuit;
    int mValue;
};

class BunchOfCards
{
  public:
    friend ifstream& operator >>(ifstream& ifs, vector <Card>);
  private:
    vector <Card> mSomeCards;
};

I am getting the following error message:

Code:

`mSomeCards' undeclared (first use this function)

when I try to do this:

Code:

ifstream& operator >>(ifstream& ifs, vector<Card>)
{
  ifs>>mSomeCards;
  return ifs;
}

Any idea how I should go about this? Thanks

Yes, I'm getting closer, I think:

Code:

class Card
{
  public:
    friend ifstream& operator >>(ifstream& is, Card& cd);  
    friend ostream& operator <<(ostream& os, Card cd);
  private:
    string mSuit;
    int mValue;
};

class BunchOfCards
{
  public:
    friend ifstream& operator >>(ifstream& ifs, vector <Card> aDeck);
  private:
    vector <Card> mSomeCards;
};

And:

Code:

ifstream& operator >>(ifstream& ifs, vector <Card> aDeck)
{
  ifs>>aDeck;
  return ifs;
}

...but what here?

Code:

int main()
{
  BunchOfCards aDeck;
  ifstream aStreamOfCards;
  aStreamOfCards.open("Deck.dat");
  while(aStreamOfCards>>aDeck)
  {
    
  system("pause");
  return 0;
}

Got error here:

Code:

int main()
{
  BunchOfCards aDeck;
  ifstream aStreamOfCards;
  aStreamOfCards.open("Deck.dat");
  while(aStreamOfCards>>aDeck)
  {
    mSomeCards.push_back(aDeck);
  }  
  system("pause");
  return 0;
}

of:

Code:

no match for `ifstream & >> BunchOfCards &'

You didn't make the change I suggested. Instead of accepting a vector as an argument to the operator >>, you need to take a BunchOfCards reference. Do that first, then fix the inside of the function as I mentioned before.