A qustion about Vectors with constructors.

Hi all

I am going to create a program a Deck ADT that represents a deck of playing cards. The Deck ADT will use a vector to store 52 individual Crad objects.

Here is my program

Code:

---


#ifndef deck_h
#define deck_h
#include <vector>
#include <cstdlib>
class Deck
{
public:
        Deck() {card.reverse(52);} // Default constructor, sets the   
                                                        initial size of 52
 
        void shuffle(); // This is what i don't know to do             


private:
     
          vector<int> card; // STL vector of type card.
};
#endif

---

I am going to create a public method to shuffle the deck. However, i feel confuse how i should code in this method.
Which return type i should use? void or int?
and can i use RANDOM method from c standard library?
Pls give me some advise, thanks.

I would use random_shuffle<>.

gg

Code:

---

Deck() {card.reverse(52);}

---

Are you sure you don't mean reserve

Onto the shuffle:
There are a couple methods you can employ, one of which is random_shuffle()

As far as the return type let me ask you this, if the function did return something, what would you use the return for?

Be aware that the random_shuffle function makes use of the rand function which of course would require you to first call srand to seed the psuedorandom number generator before you started to use it. Otherwise, the shuffling would end up being the same each time you ran the program.

reserve() doesn't set the size of the vector. It just tells the vector to allocate enough memory to be able to grow to a specific size without having to reshuffle. You probably want resize(), or better yet, in this situation, pass the deck size directly to the vector's constructor in the intialization list.

I have modified the program like this:

Code:

---

#ifndef deck_h
#define deck_h
#include <vector>
#include <cstdlib>
class Deck
{
public:
        Deck() { card.reserve(52); } // default constructor, sets the initial size of 52

        void random_shuffle(card.begin(), card.end()); // shuffle cards

        Card operator[](int index) { return card[index]; } // Overload the [] operator so that a programmer
                                                                                                          // can access each Card in the Deck using array notation.               


private:
        vector<int> card; // STL vector of type card.




};
#endif

---

This is my header file, if i just want to do the class declaration in the C++ header file only.
What should i do with the void random_shuffle function?

is it like that?

Code:

---

void random_shuffle() // Do i need to put any parameter inside the branket?

---

Thanks

You misunderstand how to use random_shuffle.

You would have something like this:

Code:

---

Class Deck
{
  public:
    void shuffle();
};

void Deck::shuffle()
{
  random_shuffle(card.begin(), card.end());
}

---

Oh, i made a big mistake with that.

Thanks for advise.

I have already re-modifed the program like this:

Code:

---

//deck.h
#ifndef deck_h
#define deck_h
#include <vector>
#include <cstdlib>
class Deck
{
public:
        Deck() { card.reserve(52); } // default constructor, sets the initial size of 52

        void shuffle(); // method of shuffle cards

        Card operator[](int index) { return card[index]; } // Overload the [] operator so that a programmer
                                                                                                          // can access each Card in the Deck using array notation.               


private:
        vector<int> card; // STL vector of type card.




};
#endif

---

Here is deck.cpp file

Code:

---

// deck.cpp
#include <cstdlib>
#include <iostream>
#include "deck.h"

void Deck::shuffle()
{
  random_shuffle(card.begin(), card.end());
}

Deck& Card::operator[]( const Deck& playingCard )

---

In my header file, I have one overload operator []

Code:

---

Card operator[](int index) { return card[index]; } // Overload the [] operator so that a programmer

---

However, Do i need to implement it in my deck.cpp file?
If yes, can anyone suggest me how to code it?
Thanks.

Until you learn the ins and outs and little quirks stick to putting just the class definations and function prototypes in your header and then put all your function definations in your cpp.

Would you pls give me an example how to figure out for the overload operator[] problem
Inside the header file
I should use:

Code:

---

Card operator[](int index)

---

and inside the cpp file, i should use it?

Code:

---

Card operator[](int index) { return card[index]; }

---

In header:

Code:

---

Card& operator[](int);

---

In source

Code:

---

Card& Deck::operator[](int index)
{
  if ( index >= 0 && index < 52 )
    return card[index];
  // otherwise do some error handling here
}

---

Oh, that's what i need to code in my program.
Thanks a lot.

Hey, if i want to know which header file is required for the method random_shuffle?

Which homepage provide this imformation?

Thanks again.

However, when i try to compile the cpp file, it has two errors:

Code:

---


Card& Deck::operator[](int index)
{
  if ( index >= 0 && index < 52 )
    return card[index];
}

error C2440: 'return' : cannot convert from 'int' to 'class Card &'
        A reference that is not to 'const' cannot be bound to a non-lvalue

---

and 1 more i think the reason is i haven't coded the #include <someting> inside the header

Code:

---

random_shuffle(card.begin(), card.end());
error C2065: 'random_shuffle' : undeclared identifier

---

Quote:

---

Originally Posted by joenching

Hey, if i want to know which header file is required for the method random_shuffle?

Which homepage provide this imformation?

Thanks again.

---

You need to include the <algorithm> header.

<algorithm> is the required header. As for which page tells you that...

http://cppreference.com/
This one apparently doesn't document the algorithm header.

http://www.sgi.com/tech/stl/
This one is ONLY about the STL.

http://msdn.microsoft.com/library/default.asp
One of the most complete ones, but it's a pain to navigate with anything but IE (as if it was impossible to implement a proper tree view in Gecko ...), quite slow and some people don't like it.

http://gcc.gnu.org/onlinedocs/libstd...3.4/index.html
Fast, but I don't know how complete or good. In any way, it seems the class list freaks out in my firefox and wanders off the screen.

I have already settled the second problem
just put #include <algorithm> will fix it.

For the first error, can anyone suggest me how i should do?

Quote:

---

Originally Posted by joenching

However, when i try to compile the cpp file, it has two errors:

Code:

---


Card& Deck::operator[](int index)
{
  if ( index >= 0 && index < 52 )
    return card[index];
}

error C2440: 'return' : cannot convert from 'int' to 'class Card &'
        A reference that is not to 'const' cannot be bound to a non-lvalue

---

and 1 more i think the reason is i haven't coded the #include <someting> inside the header

Code:

---

random_shuffle(card.begin(), card.end());
error C2065: 'random_shuffle' : undeclared identifier

---

---

change Card& to int

Or change the card member of Deck to vector<Card>. This probably makes more sense.

Thantos:
After i remodifed the program, it can be compiler, however, it has a warning message:

Code:

---

int Deck::operator[] (int index)
{
  if ( index >= 0 && index < 52 )
    return card[index];
}
 warning C4715: 'Deck::operator[]' : not all control paths return a value

---

I wanna show you my Card class, I think there should has some interact with card class.
Here is my card.h

Code:

---

#include <iostream>

using namespace std;

class Card
{
public:

    enum Rank
    {
        ACE,
        TWO,
        THREE,
        FOUR,
        FIVE,
        SIX,
        SEVEN,
        EIGHT,
        NINE,
        TEN,
        JACK,
        QUEEN,
        KING
    };

    enum Suit
    {
        SPADES,
        HEARTS,
        CLUBS,
        DIAMONDS
    };

    Card(); // Default constructor will initialize to Ace of Spades
    Card( Rank newRank, Suit newSuit );

    Rank getRank() const {return rank;}
    Suit getSuit() const {return suit;}

    void setRank( Rank newRank );
    void setSuit( Suit newSuit );

private:

    Rank rank;
    Suit suit;
};

ostream& operator<<( ostream& os, const Card& card );

---

here is card.cpp

Code:

---

#include <cassert>
#include <iostream>

#include "card.h"
                   
using namespace std;

Card::Card() :
    rank( ACE ),
    suit( SPADES )
{
}

Card::Card( Rank newRank, Suit newSuit ) :
    rank( newRank ),
    suit( newSuit )
{
}

void Card::setRank( Rank newRank )
{
    rank = newRank;
}

void Card::setSuit( Suit newSuit )
{
    suit = newSuit;
}

ostream& operator<<( ostream& os, const Card& card )
{
    switch( card.getRank() )
    {
        case Card::ACE:
            os << "Ace";
            break;
        case Card::TWO:
            os << "Two";
            break;
        case Card::THREE:
            os << "Three";
            break;
        case Card::FOUR:
            os << "Four";
            break;
        case Card::FIVE:
            os << "Five";
            break;
        case Card::SIX:
            os << "Six";
            break;
        case Card::SEVEN:
            os << "Seven";
            break;
        case Card::EIGHT:
            os << "Eight";
            break;
        case Card::NINE:
            os << "Nine";
            break;
        case Card::TEN:
            os << "Ten";
            break;
        case Card::JACK:
            os << "Jack";
            break;
        case Card::QUEEN:
            os << "Queen";
            break;
        case Card::KING:
            os << "King";
            break;
        default:
            assert( 0 );
    }

    os << " of ";

    switch( card.getSuit() )
    {
        case Card::SPADES:
            os << "Spades";
            break;
        case Card::HEARTS:
            os << "Hearts";
            break;
        case Card::CLUBS:
            os << "Clubs";
            break;
        case Card::DIAMONDS:
            os << "Diamonds";
            break;
        default:
            assert( 0 );
    }

    return os;
}

---

appericate it

CornedBee

I modified it to that:

Code:

---

vector<Card> card; // STL vector of type card.

---

it's almost work, but it still shows a error msg which is same as above when i try to compile it.

You discared Thantos' comment about doing error handling without ever doing anything like it, and now you're surprised it doesn't work?

Actually, I'd ditch the range test altogether and use vector::at to access the card, that does the range test and the error handling for you.

Quote:

---

Originally Posted by CornedBee

You discared Thantos' comment about doing error handling without ever doing anything like it, and now you're surprised it doesn't work?

Actually, I'd ditch the range test altogether and use vector::at to access the card, that does the range test and the error handling for you.

---

Doesn't at() throw an exception? If so they might not want to have their program crash just because they gave an invalid range

You mean i need to do the error handling?

Well considering you'll have to do something if they give you an index out of range, yeah you'll have to do some error handling. Either as the class developer or as the class user

It means there has 52 cards in the Deck class
if i want to show the 53 card in that class.
The deck class will throw an error exception?

Currently it will simply crash. If you use at(), it will throw a std::out_of_range.