Problems with vector.push_back()

Nerijus Vil?inskas · 2013-03-28T18:43:19

Hello everybody, Yesterday I started to program Black Jack game in console and I have problems with vectpr.push_back(), I use it to add cards from deck to players hand, for what I use CPlayer::PDraw(CDeck d) function, here it is: void PDraw( CDeck d) { cards.push_back(d.getDeck()[cardCounter]);//error, deck deletes somehow after doing one command cardCounter++; } The problem is, when I use puch back(), my deck what I pass into function somehow is changed and becomes empty, I think it has to do something with my Copy and Assignment constructors of CDeck class, here is my CDeck class: //Class representing Deck of Cards class CDeck { public: CDeck(){ pDeck= new SCard[CARD_NUMBER]; for(int i = 0; i < CARD_NUMBER; i ++) { //Assign ID to card and its suit and value pDeck.id = i; identifyCard(&pDeck); } } ~CDeck(){ delete[] pDeck; } CDeck(const CDeck &d) { operator=(d); }//error here? const CDeck &operator=(const CDeck &d) {//still mistake for(int i = 0; i < CARD_NUMBER; i++) { pDeck.id = d.pDeck.id; pDeck.type = d.pDeck.type; pDeck.num = d.pDeck.num; pDeck.val = d.pDeck.val; } return d; } void shuffleDeck() { //Shuffles Deck, but maybe more suitable with vector and rand() std::random_shuffle(pDeck, pDeck + 52); } void identifyCard(SCard* c) { c->type = suits[c->id/13]; c->val = value[c->id%13]; c->num = nums[c->id%13]; } SCard* getDeck(){return pDeck;} private: SCard* pDeck; }; Here is SCard structure: //Structure representing one card typedef struct { //Card ID convertible to its value and suit int id; //Card Value from Sce to King string val; //Card suit, Hearts etc. string type; //Cars numerical value with ace being 11 int num; }SCard; ANd lastly, my CPlayer class: //Class representing main Player class CPlayer { public: CPlayer() { bet = 0; balance = START_MONEY; counter = 0; //party begins isPlaying = true; //first move is banks isActive = false; } //Player actions funcs void PStay() { isActive = false; } void PDraw( CDeck d) { cards.push_back(d.getDeck()[cardCounter]);//error, deck deletes somehow after doing one command cardCounter++; } void PDouble(CDeck d) { PDraw(d); bet*=2; } void PMove(CDeck d) { int choise; cout << "Choose move what you like: \n1.Stay.\n2.Draw\n3.Double.\n"; cin >> choise; if(choise == 1) PStay(); if(choise == 2) PDraw(d); if(choise == 3) PDouble(d); } void PInfo() { cout << "Balance: " << balance << endl; cout << "Bet: " << bet << endl; cout << "Cards in your hand:" << endl; vector<SCard>::iterator iter; for(iter = cards.begin(); iter != cards.end(); ++iter) { cout << (*iter).val << " of " << (*iter).type << endl; } cout << "Value: " << PSum() << endl;; } void PBet() { bool isBetMade = false; while(!isBetMade) { cout << "Enter the bet between 10 to "<< balance << ": "; cin >> bet; if(bet < 10 || bet > balance) cout << "\nYou can't bet this sum. Type Again\n"; else isBetMade = true; } balance -= bet; } int PSum() { int numOfAces = 0; //nuimber of aces in hand vector<SCard>::iterator iter; for(iter = cards.begin(); iter != cards.end(); ++iter) { if((*iter).val == "Ace") numOfAces++; counter += (*iter).num; } if(counter > BLACK_JACK) { for(iter = cards.begin(); iter != cards.end(); ++iter) { if((*iter).val == "Ace") counter -= 10;// +1 and -11 if(counter <= BLACK_JACK) break; } } return counter; } bool isPlaying;//player currently playing bool isActive; // is players move private: int balance; int bet; //stores current points that player has int counter; //stores current cards in hand vector<SCard> cards; }; I regard every possible answer to this problem. When I run program and step to line where I push card into my vector representing cards in player hands it throws unhandled exception (Unhandled exception at 0x779615de in Black Jack.exe: 0xC0000005: Access violation writing location 0x76d833aa.). To be more precise it comes to constructor of CDeck and then breaks.

For Beginners

Started by kaktusas2598 March 27, 2013 02:02 PM

17 comments, last by alvaro 11 years ago

kaktusas2598

953

Author

March 28, 2013 11:11 AM

What exactly do you mean by "removing"? Removed as per SiCrane's suggestions or just removed it from your code?

If you do not supply one explicitly the compiler will generate one which might have similar problems depending on the situation.

I just removed it from my code and compiled generated constructors works just fine for me. One more question. Do anybody know how use random_shuffle() which I am using to shuffle my deck to shuffle deck diferrently every time, similar like using srand() with rand(). Cause now it shuffles the deck same way every time I run the game, so I think I need some way to seed some random number based by time every time I use random_shuffle(). Thank you.

Deltron Zero and Automator.

Brother Bob

10,350

March 28, 2013 11:28 AM

What exactly do you mean by "removing"? Removed as per SiCrane's suggestions or just removed it from your code?

If you do not supply one explicitly the compiler will generate one which might have similar problems depending on the situation.

I just removed it from my code and compiled generated constructors works just fine for me.

But as BitMaster said, the compiler generated copy constructor is as incorrect as the copy constructor you originally had. It doesn't work. Your class simply isn't set up for handling the ownership of the pointer, and neither the compiler generated copy constructor nor your original copy constructor is doing the right job. And by the way, this applies to the copy assignment operator as well.

The point is to completely disable copying by making the copy constructor and assignment operators private to ensure that you cannot copy the objects. Or, implement proper copy operators to ensure that the ownership of the pointer is handled correctly.

One more question. Do anybody know how use random_shuffle() which I am using to shuffle my deck to shuffle deck diferrently every time, similar like using srand() with rand(). Cause now it shuffles the deck same way every time I run the game, so I think I need some way to seed some random number based by time every time I use random_shuffle(). Thank you.

Seed the random number generator with something that is not pre-defined, such as time.


srand(time(NULL));

kaktusas2598

953

Author

March 28, 2013 04:51 PM

kaktusas2598, on 28 Mar 2013 - 13:09, said:

One more question. Do anybody know how use random_shuffle() which I am using to shuffle my deck to shuffle deck diferrently every time, similar like using srand() with rand(). Cause now it shuffles the deck same way every time I run the game, so I think I need some way to seed some random number based by time every time I use random_shuffle(). Thank you.

Seed the random number generator with something that is not pre-defined, such as time.

srand(time(NULL));

But I am using random_shuffle(). not rand(), does srand() also works with random_shuffle()? :o

Deltron Zero and Automator.

Brother Bob

10,350

March 28, 2013 05:02 PM

kaktusas2598, on 28 Mar 2013 - 13:09, said:

One more question. Do anybody know how use random_shuffle() which I am using to shuffle my deck to shuffle deck diferrently every time, similar like using srand() with rand(). Cause now it shuffles the deck same way every time I run the game, so I think I need some way to seed some random number based by time every time I use random_shuffle(). Thank you.

Seed the random number generator with something that is not pre-defined, such as time.

srand(time(NULL));

But I am using random_shuffle(). not rand(), does srand() also works with random_shuffle()?

Sorry, I was thinking randomness and seeding and wasn't exactly thinking about what I was actually answering. The random generator used by the two-parameter variant of std::random_shuffle is in fact implementation defined, but probably uses rand. If it does, then srand will seed std::random_shuffle.

However, you may want to use the variant with the third parameter instead, which lets you specify the random number generator yourself. I believe you can pass rand as the third parameter to make sure that it does, in fact, use rand for random numbers.

SiCrane

11,840

March 28, 2013 05:22 PM

rand() isn't a valid function for the third parameter of std::random_shuffle(). If you pass it a function, the function has to take one argument n, and return a value from 0 to n - 1. rand() doesn't take any arguments.

Brother Bob

10,350

March 28, 2013 05:31 PM

I apologize, that makes total sense.

kaktusas2598

953

Author

March 28, 2013 05:35 PM

I have read on internet, that random_shuffle really was inplemented using rand(), so srand() works! Thank you, fellow developers, for all your help!

Deltron Zero and Automator.

SiCrane

11,840

March 28, 2013 06:31 PM

It would be more accurate to say "is usually implemented using rand()". The C++ standard doesn't require standard library implementations to use rand() under the hood for the two argument version of the random_shuffle() function. I would be cautious about trusting an internet source that said this was definitely the case (unless it was referring to your particular compiler/standard library implementation).

alvaro

21,604

March 28, 2013 06:43 PM

I just checked a late draft of the C++11 standard, and SiCrane is correct. This is unfortunate, and it leaves us with two options: Either avoid using the two-argument version of random_shuffle (since the standard doesn't give you any tools to seed the source of randomness) or live our lives ignoring this oddity in the standard, and trusting that compiler writers are sensible people. If a compiler doesn't use rand as the source of randomness, I will happily stop using that compiler.

Problems with vector.push_back()

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