21点游戏，提升c编程的项目实践

21点又名黑杰克（Blackjack），起源于法国，已流传到世界各地，有着悠久的历史。现在在世界各地的赌场中都可以看到二十一点，随着互联网的发展，二十一点开始走向网络时代。该游戏由2到6个人玩，使用除大小王之外的52张牌，游戏者的目标是使手中的牌的点数之和不超过21点且尽量大。
https://baike.baidu.com/item/21%E7%82%B9/5481683?fr=aladdin
下面是根据21点游戏规则，利用c语言开发的小游戏。游戏本身多大意义，主要是可以作为一个提升c编程能力的小项目。
下面是部分源代码：/* Filename:BLACKJACK.c
Time:2018.03.24
Edit:Qin
Introduction:This program plays a game of blackjack with you.The
computer is the dealer and you are the victimer,I mean player.The dealer
gets a card that you can see.The dealer than asks if you want another
card by asking "Hit"or"Stand".If you choose hit ,the dealer gives you
another card.If you choose to stand ,the dealer draws or stands, and the
game is played out according to the cards you and the dealer have.As with
real blackjack,the dealer stands on 17.The winner is announced only after
both the player's and the dealer's hands are finished.
*/

//ANSI C standard header files appear next
#include <stdio.h>
#include <time.h>
#include <ctype.h>
#include <stdlib.h>

//Defined constants appear next
#define BELL '\a'
#define DEALER 0
#define PLAYER 1

/*Must keep two sets of totals for dealer and for player.The first set counts
Aces as 1 and the second counts Aces as 11. Unlike "real world" blackjack,this
program doesn't allow some Aces to be 1 while others Aces are 11 in the same hand.
*/
#define ACELOW 0
#define ACEHIGH 1

/*Only one global variable is used in this entire program.The variable holds 0,
which means false initially.Once the user enter his or her name in initCardsScreen(),
this variable is set to 1(for true), so the name is never asked for again the rest
of the program.
*/
int askedForName=0; //False initially

//This program's specific prototypes
void dispTitle(void);
void initCardsScreen(int cards[52],int playerPoints[2],int dealerPoints[2],int total[2],int *numCards);
int dealCard(int *numCards,int cards[52]);
void dispCard(int cardDrawn,int points[2]);
void totalIt(int points[2],int total[2],int who);
void dealerGetsCard(int *numCards,int cards[52],int dealerPoints[2]);
void playerGetsCard(int *numCards,int cards[52],int playerPoints[2]);
char getAns(char mesg[]);
void findWinner(int total[2]);

//main() function
main()
{
int numCards; //Equals 52 at beginning of each game
int cards[52],playerPoints[2],dealerPoints[2],total[2];
char ans; //For user's Hit/Stand or Yes/No response
do{
initCardsScreen(cards,playerPoints,dealerPoints,total,&numCards);
dealerGetsCard(&numCards,cards,dealerPoints);
printf("\n");
playerGetsCard(&numCards,cards,playerPoints);
do{
ans=getAns("Hit or stand (H/S)?");
if(ans=='H')
{
playerGetsCard(&numCards,cards,playerPoints);
}
} while(ans!='S');
totalIt(playerPoints,total,PLAYER); //Player's total
do{
dealerGetsCard(&numCards,cards,dealerPoints);
} while(dealerPoints[ACEHIGH]<17); //17:dealer stops
totalIt(dealerPoints,total,DEALER); //Dealer's total
findWinner(total);
ans=getAns("\nPlay again(Y/N)?");
} while(ans=='Y');
return;
}

/* This function initializes the face values of the deck of cards by putting four sets of 1~13 in the
52-card array.Also clears the screen and displays a title.
*/
void initCardsScreen(int cards[52],int playerPoints[2],int dealerPoints[2],int total[2],int *numCards)
{
…… }

/*This function gets a card for the player and updates the player's points
*/
void playerGetsCard(int *numCards,int cards[52],int playerPoints[2])
{
int newCard;
newCard=dealCard(numCards,cards);
printf("You draw: ");
dispCard(newCard,playerPoints);
}

/*This function gets a card for the dealer and updates the dealer's points
*/
void dealerGetsCard(int *numCards,int cards[52],int dealerPoints[2])
{
int newCard;
newCard=dealCard(numCards,cards);
printf("The dealer draws: ");
dispCard(newCard,dealerPoints);
}

/* This function gets a card from the deck and stores it in
either the dealer's or the player's hold of cards
*/
int dealCard(int *numCards,int cards[52])
{
int cardDrawn,subDraw;
time_t t; //Gets time for a random value
srand(time(&t)); //Seeds random-number generator
subDraw=(rand()%(*numCards)); //From 0 to numcards
cardDrawn=cards[subDraw];
//Puts top card in place of drawn one
cards[subDraw]=cards[*numCards-1];
(*numCards)--;
return cardDrawn;
}

/*Displays the last-drawn card and updates points with it
*/
void dispCard(int cardDrawn,int points[2])
{
switch(cardDrawn)
{
case(11):printf("%s\n","Jack");
points[ACELOW]+=10;
points[ACEHIGH]+=10;
break;

case(12):printf("%s\n","Queen");
points[ACELOW]+=10;
points[ACEHIGH]+=10;
break;

case(13):printf("%s\n","King");
points[ACELOW]+=10;
points[ACEHIGH]+=10;
break;

default:points[ACELOW]+=cardDrawn;

if(cardDrawn==1)
{
printf("%s\n","Ace");
points[ACEHIGH]+=11;
}
else
{
points[ACEHIGH]+=cardDrawn;
printf("%d\n",cardDrawn);
}
}
return;
}

/*Figures the total for player or dealer to see who won.
This function takes into account the fact that Ace is either
1 or 11
*/
void totalIt(int points[2],int total[2],int who)
{
/*The following routine first looks to see if the total points
counting Aces as 1 is equal to the total points counting Ace as
11. If so,or if the total points counting Aces as 11 is more than
21,the program uses the total with Aces as 1 only.
*/
if((points[ACELOW]==points[ACEHIGH])||(points[ACEHIGH]>21))
{
total[who]=points[ACELOW]; //Keep all Aces as 1
}
else
{
total[who]=points[ACEHIGH]; //Keep all Aces as 11
}

if(who==PLAYER) //Determines the message printed
{
printf("You have a total of %d\n\n",total[PLAYER]);
}
else
{
printf("The house stands with a total of %d\n\n",total[DEALER]);
}
return;
}

//Prints the winning player.
void findWinner(int total[2])
{
if(total[DEALER]==21)
{
printf("The house wins.\n");
return;
}
if((total[DEALER]>21)&&(total[PLAYER]>21))
{
printf("%s","Nobody wins.\n");
return;
}
if((total[DEALER]>=total[PLAYER])&&(total[DEALER]<21))
{
printf("The house wins.\n");
return;
}
if((total[PLAYER]>21)&&(total[DEALER]<21))
{
printf("The house wins.\n");
return;
}
printf("%s%c","You win!\n",BELL);
return;
}

//Gets the user's uppercase,single-character response
char getAns(char mesg[])
{
char ans;
printf("%s",mesg); //Prints the prompt message passed
ans=getchar();
/*The next "getchar()" is very important!
Which can discard newline,
so you can safely ignore compiler warning here
*/
getchar();
// Next is convert the lowercase letters to upper case letters.
return toupper(ans);
}

//Clear everything off the screen
void dispTitle(void)
{
int i=0;
while(i<3)
{
printf("\n");
i++;
}
printf("\n\n*Step right up to the Blackjack tables*\n\n");
return;
}由于代码太长，初始化函数void initCardsScreen省略了，具体内容可参照https://download.csdn.net/download/zhanshen112/10306315，文件里有所有源代码。