class CCard
{
public:
CCard(): m_pTile( NULL ) {}
~CCard() {}
protected:
int iValue;
int iColor;
CTile *m_pTile;
};
class CDeck : public CCard
{
public:
CDeck()
{
Deck.reserve( 56 );
int c = 1, v = 1;
for( p_Deck = Deck.begin(); p_Deck!= Deck.end(); p_Deck++ )
{
if( v <= 14 )
{
p_Deck->iValue = v;
v++;
}
else
{
p_Deck->iColor = c;
v = 1;
c+= 1;
}
}
}
~CDeck(){}
private:
vector<CCard>Deck;
vector<CCard>::iterator p_Deck;
};
inheritance (sp?) problem
Author
I am making a small card game and ran into a problem.
when I compile this code I get an error that p_Deck can't see iColor and iValue because it's protected, now I thought that I had it CCard inherited and thus all variables should be vissible. Could someone tell me what is wrong here?
First, a deck is not a card, so CDeck should not inherit from CCard.
Second, vector::reserve() preallocates memory - it doesn't actually insert elements in the vector - use vector::resize().
Third, for a deck of cards, std::deque may prove more useful than std::vector. std::random_shuffle() may also be handy.
Now, regarding your question, while CDeck is allowed to access protected CCard members via a CDeck variable (because it is derived from CCard), it is not allowed to access them via a CCard variable.
CDeck would have to be a friend of CCard to allow that.
Second, vector::reserve() preallocates memory - it doesn't actually insert elements in the vector - use vector::resize().
Third, for a deck of cards, std::deque may prove more useful than std::vector. std::random_shuffle() may also be handy.
Now, regarding your question, while CDeck is allowed to access protected CCard members via a CDeck variable (because it is derived from CCard), it is not allowed to access them via a CCard variable.
class Base{protected: int i;};class Derived : public Base{ void Foo( Derived& d ) { d.i = 0; } // OK ! void Bar( Base& b ) { b.i = 0; } // NOT OK!};CDeck would have to be a friend of CCard to allow that.
class CDeck;class CCard{public: CCard(): m_pTile( NULL ) {} ~CCard() {} protected: int iValue; int iColor; CTile *m_pTile; friend class CDeck;};class CDeck : public CCard{public: CDeck() { Deck.reserve( 56 ); int c = 1, v = 1; for( p_Deck = Deck.begin(); p_Deck!= Deck.end(); p_Deck++ ) { if( v <= 14 ) { p_Deck->iValue = v; v++; } else { p_Deck->iColor = c; v = 1; c+= 1; } } } ~CDeck(){}private: vector<CCard>Deck; vector<CCard>::iterator p_Deck;};
The main point here is that a Card is not a Deck, and a Deck is not a Card.
A Card is a Paper or is a Square, etc...
A Deck is not a type of Card, but a Deck HAS Cards. Here's an example:
Call it:
Of course this would require implementing a CCard class that has a method GetDesc() that returns a character array or string, and assigning values to all the CCard instances in the CDeck class but hey, time is short :)
A Card is a Paper or is a Square, etc...
A Deck is not a type of Card, but a Deck HAS Cards. Here's an example:
class CDeck{ CCard m_card[52]; // Creates 52 CCard Instances public: void DisplayCard(int card); { cout << "Card " << card << " is: " << m_card[card].GetDesc() << endl; }}Call it:
CDeck Deck;Deck.DisplayCard(1);Of course this would require implementing a CCard class that has a method GetDesc() that returns a character array or string, and assigning values to all the CCard instances in the CDeck class but hey, time is short :)
This topic is closed to new replies.
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