UNB/ CS/ David Bremner/ teaching/ old/ cs2023/ king-examples/ poker.c
```/*********************************************************
* From C PROGRAMMING: A MODERN APPROACH, Second Edition *
* By K. N. King                                         *
* Copyright (c) 2008, 1996 W. W. Norton & Company, Inc. *
* This program may be freely distributed for class use, *
* provided that this copyright notice is retained.      *
*********************************************************/

/* poker.c (Chapter 10, page 233) */
/* Classifies a poker hand */

#include <stdbool.h>   /* C99 only */
#include <stdio.h>
#include <stdlib.h>

#define NUM_RANKS 13
#define NUM_SUITS 4
#define NUM_CARDS 5

/* external variables */
int num_in_rank[NUM_RANKS];
int num_in_suit[NUM_SUITS];
bool straight, flush, four, three;
int pairs;   /* can be 0, 1, or 2 */

/* prototypes */
void analyze_hand(void);
void print_result(void);

/**********************************************************
* main: Calls read_cards, analyze_hand, and print_result *
*       repeatedly.                                      *
**********************************************************/
int main(void)
{
for (;;) {
analyze_hand();
print_result();
}
}

/**********************************************************
*             variables num_in_rank and num_in_suit;     *
*             checks for bad cards and duplicate cards.  *
**********************************************************/
{
bool card_exists[NUM_RANKS][NUM_SUITS];
char ch, rank_ch, suit_ch;
int rank, suit;

for (rank = 0; rank < NUM_RANKS; rank++) {
num_in_rank[rank] = 0;
for (suit = 0; suit < NUM_SUITS; suit++)
card_exists[rank][suit] = false;
}

for (suit = 0; suit < NUM_SUITS; suit++)
num_in_suit[suit] = 0;

printf("Enter a card: ");

rank_ch = getchar();
switch (rank_ch) {
case '0':           exit(EXIT_SUCCESS);
case '2':           rank = 0; break;
case '3':           rank = 1; break;
case '4':           rank = 2; break;
case '5':           rank = 3; break;
case '6':           rank = 4; break;
case '7':           rank = 5; break;
case '8':           rank = 6; break;
case '9':           rank = 7; break;
case 't': case 'T': rank = 8; break;
case 'j': case 'J': rank = 9; break;
case 'q': case 'Q': rank = 10; break;
case 'k': case 'K': rank = 11; break;
case 'a': case 'A': rank = 12; break;
}

suit_ch = getchar();
switch (suit_ch) {
case 'c': case 'C': suit = 0; break;
case 'd': case 'D': suit = 1; break;
case 'h': case 'H': suit = 2; break;
case 's': case 'S': suit = 3; break;
}

while ((ch = getchar()) != '\n')
if (ch != ' ') bad_card = true;

else if (card_exists[rank][suit])
printf("Duplicate card; ignored.\n");
else {
num_in_rank[rank]++;
num_in_suit[suit]++;
card_exists[rank][suit] = true;
}
}
}

/**********************************************************
* analyze_hand: Determines whether the hand contains a   *
*               straight, a flush, four-of-a-kind,       *
*               and/or three-of-a-kind; determines the   *
*               number of pairs; stores the results into *
*               the external variables straight, flush,  *
*               four, three, and pairs.                  *
**********************************************************/
void analyze_hand(void)
{
int num_consec = 0;
int rank, suit;

straight = false;
flush = false;
four = false;
three = false;
pairs = 0;

/* check for flush */
for (suit = 0; suit < NUM_SUITS; suit++)
if (num_in_suit[suit] == NUM_CARDS)
flush = true;

/* check for straight */
rank = 0;
while (num_in_rank[rank] == 0) rank++;
for (; rank < NUM_RANKS && num_in_rank[rank] > 0; rank++)
num_consec++;
if (num_consec == NUM_CARDS) {
straight = true;
return;
}

/* check for 4-of-a-kind, 3-of-a-kind, and pairs */
for (rank = 0; rank < NUM_RANKS; rank++) {
if (num_in_rank[rank] == 4) four = true;
if (num_in_rank[rank] == 3) three = true;
if (num_in_rank[rank] == 2) pairs++;
}
}

/**********************************************************
* print_result: Prints the classification of the hand,   *
*               based on the values of the external      *
*               variables straight, flush, four, three,  *
*               and pairs.                               *
**********************************************************/
void print_result(void)
{
if (straight && flush) printf("Straight flush");
else if (four)         printf("Four of a kind");
else if (three &&
pairs == 1)   printf("Full house");
else if (flush)        printf("Flush");
else if (straight)     printf("Straight");
else if (three)        printf("Three of a kind");
else if (pairs == 2)   printf("Two pairs");
else if (pairs == 1)   printf("Pair");
else                   printf("High card");

printf("\n\n");
}
```