Thread: now what am i doing wrong

i have the following code

Code:

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

enum Suit { SPADES = 0, HEARTS = 1, CLUBS = 2, DIAMONDS = 3};
enum Card_Value {TWO =2, THREE, FOUR, FIVE, SIX, SEVEN, EIGHT, NINE, TEN, JACK, QUEEN, KING, ACE};
typedef struct
{
    enum Suit suit;
    enum Card_Value card;
} Card;
typedef struct
{
    char player_name[10];
    Card hand[5];
}Hand;

void initalize_random_generator(void);
void shuffle_deck(Card *p_deck_index);
Card * deck(void);
int main()
{
    Card *p_deck_index;
    int i;

    initalize_random_generator();
    p_deck_index = deck();
    shuffle_deck(p_deck_index);

    for (i = 0; i < 52; i++)
    {
        printf("card at index %d has suit: %d and face value: %d\n", i, p_deck_index[i].suit, p_deck_index[i].card);
    }
    return 0;
}

void initalize_random_generator(void)
{
    srand((unsigned) time(NULL));
}

Card * deck(void)
{
    static Card deck[52];

    return deck;
}

void shuffle_deck(Card *p_deck_index)
{
    int count_cards = 0, card_found = 0;
    int i;
    int suit_value, face_value;
    while (count_cards < 52)
    {
        suit_value = rand() % 4;
        face_value = rand() % 14 + 2;
        for (i = 0; i < count_cards + 1; i++)
        {
            if (p_deck_index[i].suit == suit_value && p_deck_index[i].card == face_value)
            {
                card_found = 1;
            }
        }
        if (!card_found)
        {
            p_deck_index[i].suit = suit_value;
            p_deck_index[i].card = face_value;
            count_cards ++;
        }
        else
        {
            card_found = 0;
        }
    }
}

if i compile this i get no warning and no errors. run it as is and i get values that i shouldn't get like 0 or 1 for face value and i get the same output over and over (at least the first 5 or 6 are the same.

if i try to debug it with the built in debugger the debugger closes before it gets to the first line in main (initalize_random_generator())

if i change the modulus operator for face_value from 14 to 12 as i want values between 2 and 14 again it compiles no errors or warnings this time though i get no output and it starts thrashing the pants out of the cpu and swap.

coop

See which card you're setting in lines 67 and 68. Shouldn't that be at p_deck_index[count_cards], not p_deck_index[i]?

Also check out the Fisher-Yates shuffle algorithm.

Also, I would expect it to become an infinite loop if you change the 14 to 12 because you're trying to fill 52 slots, each with a unique value, but you have only 48 unique values. By the 49th slot you're guaranteed that all 48 values have been used, and your algorithm will keep trying and failing to find an unused value. That should chew up the CPU but shouldn't thrash swap at all (it's not memory-intensive at all).

good catch on the p_deck_index why am i trying to fill 52 slots with 48 variables 4^12 is 16,777,216
coop

a couple of questions u have declared all the functions as static what does this do?
line 54 the call to get card you pass deck + i what does this do is it equivalent to deck[i]?
line 65

Code:

deckp[k++] = (Card){ i, j };

is this the same as writing Card.suit = i and Card.card = j
lastly how do i type the UTF-8 codes into the terminal do i hold down ctrl-u while typing the rest??
many thanks
coop

A simple function to print UTF-8 string with the card, accondingly to your criteria:

Code:

// suite: { 0 /* spades */, 1 /* hearts */, 2 /* clubs */, 3 /* diamonds */ }
// card: { 0 = ace, 2 = 1, ..., 10 = 9, J = 10, Q = 11, K = 12 }
//
// returns, string with a single UTF-8 char.
char *card2utf8( int suite, int card )
{
  static char s[5] = { 0 };

  int c = 0x1f0a1;

  switch ( suite )
  {
    case 2: // clubs
      c += 0x10;
    case 3: // diamonds
      c += 0x10;
    case 1: // hearts
      c += 0x10;
  }  

  switch ( card )
  {
    case 0 ... 10:
      c += card; break;
    default:
      c += card + 1;
  }

  s[0] = 0xf0 | ((c >> 18) & 7);
  s[1] = 0x80 | ((c >> 12) & 0x3f);
  s[2] = 0x80 | ((c >> 6) & 0x3f);
  s[3] = 0x80 | (c & 0x3f);

  return s;
}

Originally Posted by cooper1200

a couple of questions u have declared all the functions as static what does this do?
line 54 the call to get card you pass deck + i what does this do is it equivalent to deck[i]?

Yep... the symbol 'deck' is a pointer to the begining of the array (or converted to).

Originally Posted by cooper1200

Code:

deckp[k++] = (Card){ i, j };

is this the same as writing Card.suit = i and Card.card = j

it is the same as writing

Code:

deckp[k].suit = i; deckp[k].card = j; k++;

Originally Posted by cooper1200

lastly how do i type the UTF-8 codes into the terminal do i hold down ctrl-u while typing the rest??

On linux, you can press Ctrl+U, release them and type the hexadecimal code of an UNICODE character and press ENTER.

Ctrl+u, release, 0 3 b 2, <enter> = β

im doing somthing wrong here i replaced all the utf8 codes that were lost with the ones you printed out below and all i get is (null) 52 times
coop

its working now i was displaying the output on x-term rather than xfce

im a little confused with the bitwise operations s0 for example or 240 with the result of ((127185 >> 18 and'ed with 7 but 127185 is 17 bits long

Originally Posted by flp1969

On linux, you can press Ctrl+U, release them and type the hexadecimal code of an UNICODE character and press ENTER.

Ctrl+u, release, 0 3 b 2, <enter> = β

if i do this on xfce terminal i get bad command or file name