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 Chapter 10Answers to Selected Exercises
1. [was #2] (a) Answers to Selected Programming Projects3. [was #4]
#include <stdbool.h> /* C99 only */
#include <stdio.h>
#include <stdlib.h>
#define NUM_CARDS 5
#define RANK 0
#define SUIT 1
/* external variables */
int hand[NUM_CARDS][2];
/* 0 1
____ ____
0 |____|____|
1 |____|____|
2 |____|____|
3 |____|____|
4 |____|____|
rank suit
*/
bool straight, flush, four, three;
int pairs; /* can be 0, 1, or 2 */
/* prototypes */
void read_cards(void);
void analyze_hand(void);
void print_result(void);
/**********************************************************
* main: Calls read_cards, analyze_hand, and print_result *
* repeatedly. *
**********************************************************/
int main(void)
{
for (;;) {
read_cards();
analyze_hand();
print_result();
}
}
/**********************************************************
* read_cards: Reads the cards into the external variable *
* hand; checks for bad cards and duplicate *
* cards. *
**********************************************************/
void read_cards(void)
{
char ch, rank_ch, suit_ch;
int i, rank, suit;
bool bad_card, duplicate_card;
int cards_read = 0;
while (cards_read < NUM_CARDS) {
bad_card = false;
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;
default: bad_card = true;
}
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;
default: bad_card = true;
}
while ((ch = getchar()) != '\n')
if (ch != ' ') bad_card = true;
if (bad_card) {
printf("Bad card; ignored.\n");
continue;
}
duplicate_card = false;
for (i = 0; i < cards_read; i++)
if (hand[i][RANK] == rank && hand[i][SUIT] == suit) {
printf("Duplicate card; ignored.\n");
duplicate_card = true;
break;
}
if (!duplicate_card) {
hand[cards_read][RANK] = rank;
hand[cards_read][SUIT] = suit;
cards_read++;
}
}
}
/**********************************************************
* 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 rank, suit, card, pass, run;
straight = true;
flush = true;
four = false;
three = false;
pairs = 0;
/* sort cards by rank */
for (pass = 1; pass < NUM_CARDS; pass++)
for (card = 0; card < NUM_CARDS - pass; card++) {
rank = hand[card][RANK];
suit = hand[card][SUIT];
if (hand[card+1][RANK] < rank) {
hand[card][RANK] = hand[card+1][RANK];
hand[card][SUIT] = hand[card+1][SUIT];
hand[card+1][RANK] = rank;
hand[card+1][SUIT] = suit;
}
}
/* check for flush */
suit = hand[0][SUIT];
for (card = 1; card < NUM_CARDS; card++)
if (hand[card][SUIT] != suit)
flush = false;
/* check for straight */
for (card = 0; card < NUM_CARDS - 1; card++)
if (hand[card][RANK] + 1 != hand[card+1][RANK])
straight = false;
/* check for 4-of-a-kind, 3-of-a-kind, and pairs by
looking for "runs" of cards with identical ranks */
card = 0;
while (card < NUM_CARDS) {
rank = hand[card][RANK];
run = 0;
do {
run++;
card++;
} while (card < NUM_CARDS && hand[card][RANK] == rank);
switch (run) {
case 2: pairs++; break;
case 3: three = true; break;
case 4: four = true; break;
}
}
}
/**********************************************************
* 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");
}
5. [was #6]
#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 read_cards(void);
void analyze_hand(void);
void print_result(void);
/**********************************************************
* main: Calls read_cards, analyze_hand, and print_result *
* repeatedly. *
**********************************************************/
int main(void)
{
for (;;) {
read_cards();
analyze_hand();
print_result();
}
}
/**********************************************************
* read_cards: Reads the cards into the external *
* variables num_in_rank and num_in_suit; *
* checks for bad cards and duplicate cards. *
**********************************************************/
void read_cards(void)
{
bool card_exists[NUM_RANKS][NUM_SUITS];
char ch, rank_ch, suit_ch;
int rank, suit;
bool bad_card;
int cards_read = 0;
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;
while (cards_read < NUM_CARDS) {
bad_card = false;
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;
default: bad_card = true;
}
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;
default: bad_card = true;
}
while ((ch = getchar()) != '\n')
if (ch != ' ') bad_card = true;
if (bad_card)
printf("Bad card; ignored.\n");
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;
cards_read++;
}
}
}
/**********************************************************
* 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 ace-low straight */
if (num_consec == NUM_CARDS - 1 &&
num_in_rank[0] > 0 && num_in_rank[NUM_RANKS-1] > 0) {
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");
}
Copyright © 2008, 1996 W. W. Norton & Company, Inc. All rights reserved. |