最近沉迷于《NetHack》、《DCSS》等字符界面游戏，对其很感兴趣，于是用C语言写了个字符界面的井字棋小游戏，作为练手。代码写得不好。欢迎大家指教。
编写时遇到了一些问题，我原先准备用循环，直到读取到正确的输入。可该死的getchar函数，在读取后，又把回车又传给下次循环，我不得不对其进行处理。
设定井字棋的AI时，有个有趣的地方就是，先下四个角比先下中心优势更大，这违背了我以前的直觉。
1 #include <stdio.h>
2 #include <ctype.h>
3 #include <string.h>
4 #include <stdlib.h>
5 #include <time.h>
6
7 void drawBoard(char *board) //绘制棋盘
8 {
9 printf("%c|%c|%c\n", board[7], board[8], board[9]);
10 puts("-+-+-");
11 printf("%c|%c|%c\n", board[4], board[5], board[6]);
12 puts("-+-+-");
13 printf("%c|%c|%c\n", board[1], board[2], board[3]);
14 puts("-+-+-");
15 }
16
17 char inputPlayerLetter() //玩家选择棋子
18 {
19 char letter;
20 puts("你想用X还是O?");
21 do{
22 letter = toupper(getchar());
23 if (letter == '\n')
24 continue;
25 if (letter != 'X' && letter != 'O')
26 puts("你想用X还是O?");
27 }while (letter != 'X' && letter != 'O');
28
29 return letter;
30
31 }
32
33 void makeMove(char *board,char letter,int move) //落子
34 {
35 board[move] = letter;
36 }
37
38 _Bool isWinner(char *bo, char le) //判定是否获胜
39 {
40 return ((bo[7] == le && bo[8] == le && bo[9] == le) ||
41 (bo[4] == le && bo[5] == le && bo[6] == le) ||
42 (bo[1] == le && bo[2] == le && bo[3] == le) ||
43 (bo[7] == le && bo[4] == le && bo[1] == le) ||
44 (bo[8] == le && bo[5] == le && bo[2] == le) ||
45 (bo[9] == le && bo[6] == le && bo[3] == le) ||
46 (bo[7] == le && bo[5] == le && bo[3] == le) ||
47 (bo[9] == le && bo[5] == le && bo[1] == le));
48 }
49
50 const char getBoardCopy(char *board) //复制棋盘，让电脑预判可能出现的情况
51 {
52 char boardCopy[10];
53 for (int i = 1; i < 10; i++)
54 boardCopy[i] = board[i];
55 return *boardCopy;
56 }
57
58 _Bool isSpaceFree(char *board,int move) //判断棋盘上是否为空
59 {
60 return board[move] == ' ';
61 }
62
63 int getPlayerMove(char *board) //读取玩家棋子移动
64 {
65 puts("你下一步走哪里？（1-9）");
66 int move;
67 do {
68 move = getchar() - '0';
69 if (move == '\n' - '0')
70 continue;
71 if (move < 1 || move > 9 || !isSpaceFree(board, move))
72 puts("你下一步走哪里？（1-9）");
73 }while (move < 1 || move > 9 || !isSpaceFree(board, move));
74 return move;
75 }
76
77 int chooseRandomMoveFromList(char *board,char *movelist, int n) //随机读取计算机可移动的位置
78 {
79 int possibleMove[4]; //每轮选择最多只有四个
80 int j = 0;
81 for (int i = 0; i < n; i++)
82 if (isSpaceFree(board, movelist[i] - '0'))
83 possibleMove[j++] = movelist[i] - '0';
84
85 if (j != 0)
86 return possibleMove[rand()%j];
87 else
88 return 0;
89 }
90
91 int getComputerMove(char board[], char computerLetter) //获得计算机的移动
92 {
93 char playerLetter;
94 char boardCopy[10];
95 if (computerLetter == 'X') //根据计算机的棋子，判断玩家棋子
96 playerLetter = 'O';
97 else
98 playerLetter = 'X';
99
100 for (int i = 1; i < 10; i++){ //如果下一步可获胜，下那一步
101 strcpy(boardCopy, board);
102 if (isSpaceFree(boardCopy, i)) {
103 makeMove(boardCopy, computerLetter,i);
104 if (isWinner(boardCopy, computerLetter))
105 return i;
106 }
107 }
108
109 for (int i = 1; i < 10; i++){ //如果下一步玩家会获胜，占那个位置
110 strcpy(boardCopy,board);
111 if (isSpaceFree(boardCopy, i)) {
112 makeMove(boardCopy, playerLetter,i);
113 if (isWinner(boardCopy, playerLetter))
114 return i;
115 }
116 }
117
118 int move; //如果下一步不是决胜步
119 move = chooseRandomMoveFromList(board, "1379", 4); //四个角优先
120 if (move != 0)
121 return move;
122
123 move = chooseRandomMoveFromList(board, "5", 1); //中间
124 if (move != 0)
125 return move;
126
127 return chooseRandomMoveFromList(board, "2468", 4); //剩下的位置
128 }
129
130 _Bool isBoardFull(char *board) //判断棋盘是否满了
131 {
132 for (int i = 1; i < 10; i++)
133 if (isSpaceFree(board, i))
134 return 0;
135 return 1;
136 }
137
138 _Bool isAgain() //再来一局
139 {
140 char again;
141 do{
142 again = tolower(getchar());
143 if (again == '\n')
144 continue;
145 if (again != 'n' && again != 'y')
146 puts("请输入y或n。");
147 }while (again != 'n' && again != 'y');
148
149 if (again == 'y')
150 return 1;
151 else
152 return 0;
153 }
154
155
156 int main()
157 {
158 puts("欢迎来玩井字棋！") ;
159
160 while(1) { //游戏
161 char theBoard[10];
162 for (int i = 1; i < 10; i++) //将棋盘设为空白
163 theBoard[i] = ' ';
164 char playerLetter = inputPlayerLetter(); //获得玩家所选的棋子
165 char computerLetter = (playerLetter == 'X')?'O': 'X' ;
166 //获得计算机的棋子
167 _Bool isTurnPlayer; //设定是否是玩家回合
168 int move;
169 srand((unsigned)time(NULL)); //随机先后手
170 if (rand() % 2) {
171 isTurnPlayer = 0;
172 puts("电脑先走。");
173 }else {
174 isTurnPlayer = 1;
175 puts("玩家先走。");
176 }
177 _Bool gameIsPlaying = 1; //设定游戏是否进行
178
179 while (gameIsPlaying) {
180
181 if (isTurnPlayer) { //如果是玩家回合
182 drawBoard(theBoard);
183 move = getPlayerMove(theBoard);
184 makeMove(theBoard, playerLetter, move);
185
186 if (isWinner(theBoard, playerLetter)) { //如果获胜
187 drawBoard(theBoard);
188 puts("太棒了！你获胜了！");
189 gameIsPlaying = 0;
190 }
191
192 else { //如果平局
193 if (isBoardFull(theBoard)) {
194 drawBoard(theBoard);
195 puts("平局了！");
196 break;
197 }
198 else //设定轮到计算机
199 isTurnPlayer = 0;
200 }
201 }
202
203 else { //轮到计算机了
204 move = getComputerMove(theBoard, computerLetter);
205 makeMove(theBoard, computerLetter, move);
206 if (isWinner(theBoard, computerLetter)) { //如果获胜
207 drawBoard(theBoard);
208 puts("电脑打败了你！你输了。");
209 gameIsPlaying = 0;
210 } else { //平局
211 if (isBoardFull(theBoard)) {
212 drawBoard(theBoard);
213 puts("平局了！");
214 break;
215 } else // 设定轮到玩家
216 isTurnPlayer = 1;
217 }
218 }
219 }
220 puts("再来一局？（yes或no）");
221 if (!isAgain())
222 break;
223 }
224 return 0;
225 }
来源：oschina
链接：https://my.oschina.net/u/4382160/blog/3379236