Why are parameters changing from one function to another in a class? - c++

Question

I am creating a program called 3 card high card. I am using deck, card, and hand classes. The point of the program is to compare the players hand and the computers hand. Whoever has the highest card wins. If the highest two cards from each hand are equal, then the highest of the two middle cards wins, and if those are equal, the highest of the lowest cards. If not, it's a tie. My problem is where the compare function is comparing two hands. I am getting erroneous results for my computer high card, and my computer middle card (c.hc and c.mc). The results are correct in the sort function, but when they are pulled up in the compare function, it's not the right numbers. However, the players hc, mc, and lc are correct as well as the computers lc.
Disregard the strange words in my compare function. I have them there to figure out where the program is pulling the winner result in my if statements. Also disregard how weird it looks that the results of hc, mc, and lc come after the word "winner is". I only did this to see if my strange results were a result of the wrong numbers being in those parameters, and yes that was the problem.
Here is my main.cpp:
#include "3chc.h"
#include <iostream>
#include <cstdlib>
#include <ctime>
using namespace std;
int main() {
srand(time(0));
Deck d;
d.shuffle();
cout << "computer: " << endl;
Hand comp(3);
comp.dealFrom(d);
comp.reveal();
comp.sort();
cout << "player: " << endl;
Hand player(3);
player.dealFrom(d);
player.reveal();
player.sort();
cout << "Winner is " << player.compare(comp, player) << endl;
return 0;
}
--------------------------------------------
here is my 3chc.h:
//3chc.h Deck, Card, and Hand classes
#include <iostream>
#include <string>
class Card {
friend class Deck;
private:
int card_index; //card number 0 to 51
Card(int index) { card_index = index; } //made this private so user can't say card at index 100..can use it because of friend class
public:
Card() { card_index = 52; }
char suit() const;
char value() const;
std::string str() const;
int getValue(std::string c);
};
class Deck {
private:
Card cards[52];
int pos;
public:
Deck();
Card deal() { return cards[pos++]; };
void shuffle();
int size() const { return 52 - pos; };
};
class Hand {
friend class Deck;
friend class Card;
private:
int handSize;
int hc; //high card
int mc; //middle card
int lc; //low card
Card myCards[];
public:
Hand() { handSize = 1; };
Hand(int n) { handSize = n; };
void dealFrom(Deck& d);
void reveal();
//int getHandValues();
int total();
void sort();
std::string compare(Hand& c, Hand&p);
};
std::ostream& operator<< (std::ostream& out, const Card& c);
----------------------------------------------
and here is my 3chc.cpp:
//3chc.cpp - Implementations of the Deck, Card, and Hand classes
#include "3chc.h"
#include <cstdlib>
char Card::suit() const {
static char suits[] = { 'H', 'S', 'D', 'C' };
//return card_index < 52 ? suits[card_index % 4] : 'X';
return suits[card_index % 4];
}
char Card::value() const {
static char values[] =
{ '2', '3', '4', '5', '6', '7', '8', '9', 'T', 'J', 'Q', 'K', 'A' };
//return card_index < 52 ? values[card_index / 4] : 'X';
return values[card_index / 4];
}
std::string Card::str() const {
std::string s;
s += value();
s += suit();
return s;
}
Deck::Deck() {
for (int i = 0; i < 52; i ++) {
// Card c(i);
// cards[i] = c;
cards[i] = Card(i);
}
pos = 0;
}
void Deck::shuffle() {
for (int i = 0; i < 52; i++) {
int j = rand() % 52;
Card tmp = cards[i];
cards[i] = cards[j];
cards[j] = tmp;
}
pos = 0;
}
std::ostream& operator<< (std::ostream& out, const Card& c) {
out << c.str();
return out;
}
int Card::getValue(std::string c) {
char v = c[0];
int val = v - '0';
if (val > 9) {
switch(v){
case 'T':
val = 10;
break;
case 'J':
val = 11;
break;
case 'Q':
val = 12;
break;
case 'K':
val = 13;
break;
case 'A':
val = 14;
}
}
return val;
}
void Hand::dealFrom(Deck& d) {
for(int i = 0; i < handSize; i++)
myCards[i] = d.deal();
}
void Hand::reveal(){
for (int i = 0; i < handSize; i++)
std::cout << myCards[i] << " " << std::endl;
}
int Hand::total() {
int total = 0;
for (int i = 0; i < handSize; i ++) {
total += myCards[i].getValue(myCards[i].str());
}
return total;
}
void Hand::sort() {
hc = myCards[0].getValue(myCards[0].str());
mc = myCards[1].getValue(myCards[1].str());
lc = myCards[2].getValue(myCards[2].str());
int temp = 0;
if (mc > hc) {
temp = mc;
mc = hc;
hc = temp;
};
if (lc > hc) {
temp = lc;
lc = hc;
hc = temp;
};
if (lc > mc) {
temp = lc;
lc = mc;
mc = temp;
};
std::cout << "hc = " << hc << ", mc = " << mc << ", lc = " << lc << std::endl;
}
std::string Hand::compare(Hand& c, Hand&p) {
std::string winner;
while (c.hc == p.hc) {
if (c.mc == p.mc) {
if (c.lc == p.lc){
winner = "tie";
} else if (c.lc > p.lc) {
winner = "cat";
} else if (c.lc < p.lc) {
winner = "pig";
}
} else if (c.mc > p.mc) {
winner = "cell";
} else if (c.mc < p.mc) {
winner = "penguin";
}
}
if (c.hc > p.hc) {
winner = "computer";
}
if (c.hc < p.hc) {
winner = "player";
}
std::cout << "c hc = " << c.hc << " mc= " << c.mc << " lc= " << c.lc << std::endl;
std::cout << "p hc = " << p.hc << " mc= " << p.mc << " lc= " << p.lc << std::endl;
return winner;
}
I expect to have the c.hc and c.mc to be equal to what they are in the sort function. I apologize if I didn't write this post correctly. I have never posted here before. This assignment is due tonight at midnight, and I could not find the answer to my question anywhere else on this site. Your help is greatly appreciated.

Answer 1

Card myCards[]; is a pointer, not an array. You don't allocate memory for it but dereference it. That's undefined behavior and probably the source of your problem.
Use std::vector<Card> myCards; instead of Card myCards[]; and set the vector size in the constructors
Hand() { handSize = 1; myCards.resize(1); }
and
Hand(int n) { handSize = n; myCards.resize(n); }
The sort function only works with 3 cards. You could use a fixed hand size of 3 as a quick fix
Card myCards[3];
instead of the fix with std::vector.