Intermittent Failure with Blackjack code - c

Question

The purpose of this code is to play a simulated game of Blackjack. The 'Dealer' is automated and will deal two cards to itself and stop when it wins/busts or hits 17. Then the user draws until he/she is satisfied. Then a winner is determined.
I've run into a brick wall because the code compiles fine, but when it runs it will either work (and by work I mean not work as intended but it will run) or it will crash.
I have no idea how this can happen only some of the time and not all of the time and I need some help.
Here is my code:
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define SIZE 52
#define LIMIT 21
enum faces{Ace = 0, Jack = 10, Queen, King};
char * facecheck(int d);
void shuffle( int deck[]);
int draw(int deck[SIZE]);
void printcards(int hand[], int numCards);
int dealer(int deck[]);
int player(int deck[]);
int value(int yourhand[]);
int victory(int d, int p);
int i, numCards = 1;
int top = 52;
int preValue = 0;
int count = 2;
int main()
{
int deck[SIZE], i, a;
int d, p;
char suits[4][9] =
{
"Hearts",
"Diamonds",
"Clubs",
"Spades"};
srand( time( NULL ) ) ;
for(i = 0; i<SIZE; i++)
{
deck[i] = i;
};
shuffle(deck);
d = dealer(deck);
p = player(deck);
victory(d, p);
return 0;
}
char * facecheck(int d)
{
static char * face[] =
{
"Ace",
"Jack",
"Queen",
"King" };
if(d == Ace)
return face[0];
else
{
if(d == Jack)
return face[1];
else
{
if(d == Queen)
return face[2];
else
{
if(d == King)
return face[3];
}
}
}
}
void shuffle( int deck[])
{
int i, j, temp;
for(i = 0; i < SIZE; i++)
{
j = rand() % SIZE;
temp = deck[i];
deck[i] = deck[j];
deck[j] = temp;
}
printf("The deck has been shuffled \n");
}
int draw(int deck[SIZE])
{
int numCards = 1;
int i;
int hand[numCards];
int card;
for(i = 0; i < numCards && top > 0; i++)
{
card = deck[top-1];
hand[i] = card;
top--;
}
return card;
}
void printcards(int hand[], int numCard)
{
char suits[4][9] =
{
"Hearts",
"Diamonds",
"Clubs",
"Spades"};
for(i = 0; i < numCard; i++)
{
int card = hand[i];
if(card%13 == 0 || card%13 == 10 || card%13 == 11 || card%13 == 12)
printf("%s ", facecheck(card%13) );
else
printf("%d ", card%13+1);
printf("of %s \n", suits[card/13]);
}
}
int dealer(int deck[])
{
int x;
int a;
int yourhand[10];
int handIndex = 0;
int cardLimit;
int dealerValue;
yourhand[handIndex] = draw(deck);
yourhand[handIndex] = draw(deck);
printf("The Dealers second card is:");
printcards(yourhand, handIndex+1);
cardLimit = value(yourhand);
do
{
if(cardLimit == LIMIT)
{
printcards(yourhand, handIndex+1);
dealerValue = cardLimit;
return dealerValue;
}
if(cardLimit > LIMIT)
{
printcards(yourhand, handIndex+1);
dealerValue = cardLimit;
return dealerValue;
}
if(cardLimit == 17)
{
printcards(yourhand, handIndex+1);
dealerValue = cardLimit;
return dealerValue;
}
if(cardLimit <= 16)
{
yourhand[handIndex] = draw(deck);
cardLimit = value(yourhand);
}
}
while(cardLimit <= LIMIT);
handIndex++;
}
int player(int deck[])
{
int x;
int a;
int yourhand[10];
int cardLimit;
int playerValue;
int handIndex = 2;
yourhand[handIndex] = draw(deck);
yourhand[handIndex] = draw(deck);
cardLimit = value(yourhand);
printf("Your hand is: /n");
printcards(yourhand, handIndex+1);
printf("%d /n" , cardLimit);
do
{
if(cardLimit == LIMIT)
{
printcards(yourhand, handIndex+1);
playerValue = cardLimit;
return playerValue;
}
if(cardLimit > LIMIT)
{
printcards(yourhand, handIndex+1);
playerValue = cardLimit;
return playerValue;
}
else
{
printf("What would you like to do: Press 1 to Hit. 2 to Stay. \n");
scanf("%d" , &x);
if(x == 1)
{
yourhand[handIndex] = draw(deck);
cardLimit == value(yourhand);
}
else
{
printf("Player choses to stay \n");
return playerValue;
}
}
}
while(cardLimit <= LIMIT);
handIndex++;
}
int value(int yourhand[])
{
int faceValue = 10;
int cardValue[count];
int aceValue = 11;
int card[count];
int value;
int curvalue;
for(i = 0; i < count; i++)
{
card[i] = yourhand[i];
}
for(i = 0; i < count; i++)
{
cardValue[i] = card[i]%13;
}
if(cardValue[0] >= 10 && cardValue[1] >= 10)
{
value = 20;
}
if(cardValue[0] < 10 && cardValue[1] < 10)
{
value = cardValue[0] + cardValue[1];
}
if(cardValue[0] >= 10 && cardValue[1] < 10)
{
value = faceValue + cardValue[1];
}
if(cardValue[0] < 10 && cardValue[1] >= 10)
{
value = faceValue + cardValue[0];
}
if(cardValue[0] == 0 && cardValue[1] == 0)
{
value = 12;
}
if(cardValue[0] == 0 && cardValue[1] >= 10)
{
value = 21;
}
if(cardValue[1] == 0 && cardValue[0] >= 10)
{
value = 21;
}
if(cardValue[0] == 0 && cardValue[1] < 10)
{
value = aceValue + cardValue[1];
}
if(cardValue[1] == 0 && cardValue[0] < 10)
{
value = aceValue + cardValue[0];
}
preValue = value;
if(count > 2)
{
if(cardValue[count] != 0)
{
value = curvalue;
value = preValue + curvalue;
}
else
{
if(cardValue[count] + preValue > LIMIT)
{
value = preValue + 1;
}
else
{
value = cardValue[count] + aceValue;
}
}
}
count++;
return value;
}
int victory(int d, int p)
{
if(d > p)
printf("Dealer Wins \n");
else
printf("Player Wins");
}

Answer 1

In your code
int dealer(int deck[])
{
int handIndex = 0;
int yourhand[10];
yourhand[handIndex] = draw(deck);
yourhand[handIndex] = draw(deck);
you never change handIndex, so these two assignments are to the same element (ie, the second draw overwrites the first)
cardLimit = value(yourhand);
now, having written to yourhand[0] twice, and without initialising any other elements, you call value which expects yourhand[0] and yourhand[1] to be initialised.
This should be visible under valgrind (you're reading random values from uninitialized memory).