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Polymorphism and Arrays
Posted: Mon Jan 24, 2011 9:35 pm
by Maevik
I'm trying to create a class Deck (IE a deck of cards) that works with arrays of class Card. The part I'm having trouble with is that I want this deck to work with all kinds of cards and am therefore working with classes that inherit the class Card (In this case a class ResourceCard : public Card.) What I would like to be able to do is initialize an instance of Deck with an array of ResourceCard. Since they will have different memory sizes, I'm not sure polymorphism/casting can help me.
Code: Select all
int main()
{
ResourceCard resourceCard;
ResourceCard resourceCards[5];
//enum Resource { NONE, WATER, FOREST, HILL, MOUNTAIN , ANY };
resourceCard.setType( ANY );
resourceCards[0] = resourceCard;
resourceCard.setType( WATER );
resourceCards[1] = resourceCard;
resourceCard.setType( FOREST );
resourceCards[2] = resourceCard;
resourceCard.setType( HILL );
resourceCards[3] = resourceCard;
resourceCard.setType( MOUNTAIN );
resourceCards[4] = resourceCard;
Deck deck( resourceCards , 5 );
cin.get();
return 0;
}
Code: Select all
//The constructor I'm using
Deck::Deck( Card p_newCards[] , int p_count )
{
cardsInDeck = new Card[DECK_SIZE_LIMIT];
count = 0;
discardedCards = new Card[DECK_SIZE_LIMIT];
discardCount = 0;
lastDrawnCard = NULL;
if( p_count <= DECK_SIZE_LIMIT && p_count > 0)
{
count = p_count;
for( int i = 0 ; i < count ; i++ )
{
cardsInDeck[i] = p_newCards[i]; //This line causes the program crash on it's second iteration
}
}
}
So I realize I'm accessing memory I shouldn't since I'm sending an array of ResourceCard which takes up more memory than regular old Card. My question is, how do I fix this? It seems to me there should be a way to do this (or at least something like this.)
Re: Polymorphism and Arrays
Posted: Tue Jan 25, 2011 5:20 am
by adikid89
use a vector of dynamically allocated Cards? vector<Card*> cards; Since they're pointers polymorphism will work.
Re: Polymorphism and Arrays
Posted: Tue Jan 25, 2011 12:45 pm
by thejahooli
adikid89 wrote:use a vector of dynamically allocated Cards? vector<Card*> cards; Since they're pointers polymorphism will work.
You could just use an array of pointers to ResourceCards, a vector is not necessarily needed. Then you could just do this.
Code: Select all
ResourceCard *resourceCards[5];
resourceCards[0] = new ResourceCard();
resourceCrads[0]->SetType(/*Insert Type*/);
// And so on for all the cards
Re: Polymorphism and Arrays
Posted: Tue Jan 25, 2011 2:26 pm
by D-e-X
thejahooli wrote:adikid89 wrote:use a vector of dynamically allocated Cards? vector<Card*> cards; Since they're pointers polymorphism will work.
You could just use an array of pointers to ResourceCards, a vector is not necessarily needed. Then you could just do this.
Code: Select all
ResourceCard *resourceCards[5];
resourceCards[0] = new ResourceCard();
resourceCrads[0]->SetType(/*Insert Type*/);
// And so on for all the cards
Code: Select all
const int NUM_RESOURCE_CARDS = 5;
ResourceCard* resourceCards[NUM_RESOURCE_CARDS];
for(int i = 0; i < NUM_RESOURCE_CARDS; ++i)
{
resourceCards[i] = new ResourceCard;
// codez . . .
}
//moar codez . . .
Because I can
Re: Polymorphism and Arrays
Posted: Tue Jan 25, 2011 3:02 pm
by thejahooli
D-e-X wrote:
Code: Select all
const int NUM_RESOURCE_CARDS = 5;
ResourceCard* resourceCards[NUM_RESOURCE_CARDS];
for(int i = 0; i < NUM_RESOURCE_CARDS; ++i)
{
resourceCards[i] = new ResourceCard;
// codez . . .
}
//moar codez . . .
Because I can
But then they would have to be the same type, whereas in his example he uses five different types for his cards.
Re: Polymorphism and Arrays
Posted: Tue Jan 25, 2011 3:51 pm
by GroundUpEngine
Your idea works fine (doesn't crash), unless i got the wrong idea here?
Code: Select all
#include <iostream>
using namespace std;
class Card
{
public:
};
enum Resource { NONE, WATER, FOREST, HILL, MOUNTAIN , ANY };
class ResourceCard : public Card
{
public:
Resource res;
void setType(Resource r)
{
res = r;
}
};
#define DECK_SIZE_LIMIT 50
class Deck
{
public:
Card *cardsInDeck, *discardedCards, *lastDrawnCard;
int count, discardCount;
//The constructor I'm using
Deck( Card p_newCards[] , int p_count )
{
cardsInDeck = new Card[DECK_SIZE_LIMIT];
count = 0;
discardedCards = new Card[DECK_SIZE_LIMIT];
discardCount = 0;
lastDrawnCard = NULL;
if( p_count <= DECK_SIZE_LIMIT && p_count > 0)
{
count = p_count;
for( int i = 0 ; i < count ; i++ )
{
cout << "i:" << count << endl;
cardsInDeck[i] = p_newCards[i];
}
}
}
};
int main()
{
ResourceCard resourceCard;
ResourceCard resourceCards[5];
//enum Resource { NONE, WATER, FOREST, HILL, MOUNTAIN , ANY };
resourceCard.setType( ANY );
resourceCards[0] = resourceCard;
resourceCard.setType( WATER );
resourceCards[1] = resourceCard;
resourceCard.setType( FOREST );
resourceCards[2] = resourceCard;
resourceCard.setType( HILL );
resourceCards[3] = resourceCard;
resourceCard.setType( MOUNTAIN );
resourceCards[4] = resourceCard;
Deck deck( resourceCards , 5 );
cin.get();
return 0;
}
However you can use polymorphism, and cast up. then slap a function in, so you can identify the card type;
Code: Select all
// in main function
Card *res = new ResourceCard;
// into class Card
virtual string type()
{
return "Card";
}
// into class ResourceCard
string type()
{
return "ResourceCard";
}