.. _step3: 3 增加交互功能 ================= .. toctree:: :maxdepth: 2 3.1 用户选择棋子 ````````````````` 定义变量 ``piece`` 存放用户选择的棋子 .. code-block:: c++ string piece; // 存放用户选择的棋子 cout << "你选择棋子 O 还是 X ："; cin >> piece; 3.2 给出提示的棋盘 ``````````````````` .. image:: 3.1.png 这无非是把空白换成数字 1～9,棋盘每个位置都标上了序号，方便用户选择下棋的位置。修改下 ``cout`` 的输出语句即可： .. code-block:: c++ string boundary = "+---+---+---+"; string sidebar(6, ' '); //空白的左边栏 cout << "棋盘如下：" << endl; cout << sidebar << boundary << endl; cout << sidebar << "| " << 1 << " | " << 2 << " | " << 3 << " |" << endl; cout << sidebar << boundary << endl; cout << sidebar << "| " << 4 << " | " << 5 << " | " << 6 << " |" << endl; cout << sidebar << boundary << endl; cout << sidebar << "| " << 7 << " | " << 8 << " | " << 9 << " |" << endl; cout << sidebar << boundary << endl; 3.3 用户下棋 `````````````` 定义存放用户棋子坐标的变量 .. code-block:: c++ int board_x, board_y, board_number; // 存放用户的棋子坐标 在上面第二步的时候，棋盘里给出了提示，棋盘每个位置都标上了序号，让用户选择。这里定义 ``board_number`` 存放用户选择的序号。接下来，把序号转换为棋盘位置的具体坐标，利用 ``switch`` 语句： .. code-block:: c++ cout << "请输入下棋的位置序号（1～9）："; cin >> board_number; switch (board_number) { case 1 : board_x = 0, board_y = 0; break; case 2 : board_x = 0, board_y = 1; break; case 3 : board_x = 0, board_y = 2; break; case 4 : board_x = 1, board_y = 0; break; case 5 : board_x = 1, board_y = 1; break; case 6 : board_x = 1, board_y = 2; break; case 7 : board_x = 2, board_y = 0; break; case 8 : board_x = 2, board_y = 1; break; case 9 : board_x = 2, board_y = 2; break; } 判断用户下棋的位置上是否已经存在棋子 .. code-block:: c++ while (mark[board_x][board_y] == " O " || mark[board_x][board_y] == " X " ) { cout << "棋盘上已经存在棋子，请重新输入：" << endl; cout << "请输入下棋的位置序号（1～9）："; cin >> board_number; switch (board_number) { case 1 : board_x = 0, board_y = 0; break; case 2 : board_x = 0, board_y = 1; break; case 3 : board_x = 0, board_y = 2; break; case 4 : board_x = 1, board_y = 0; break; case 5 : board_x = 1, board_y = 1; break; case 6 : board_x = 1, board_y = 2; break; case 7 : board_x = 2, board_y = 0; break; case 8 : board_x = 2, board_y = 1; break; case 9 : board_x = 2, board_y = 2; break; } } mark[board_x][board_y] = " " + piece + " "; // 经过判断后，用户才下棋成功 3.4 重新实现计算机下棋 ```````````````````````` 每一轮都是用户先手，计算机后手。如果前面四轮都没有决出胜负，最后一步就轮到用户。用户下完之后还没有赢，就是出现了平局，按照程序的逻辑，用户下完轮到计算机。计算机随机选择下棋位置的时候，都要先判断这个位置是否存在棋子，如果存在则继续随机选择，但是平局的时候，棋盘里都下满棋子了，这样计算机就是不停地循环随机选择下棋的位置。这时应该判断为平局，跳出循环，结束游戏。 .. code-block:: c++ for (int i = 0; i < 5; ++i) { int x, y; // 定义计算机下棋的坐标 x = random(3), y = random(3); // 随机用法请参见 2.1 while (mark[x][y] != " " && i < 4) // 判断是否棋盘是否已经存在这个棋子 { // 如果进行到第五轮，最后一个棋子是用户下， x = random(3); // 而不是计算机 y = random(3); } } 3.5 计数下了几轮 `````````````````` 定义变量 ``step`` 作为计数器，显示下棋到了第几轮了。 .. code-block:: c++ int step; // 计算是第几步 for (int i = 0; i < 5; ++i) { step = i + 1; } 3.6 判断输赢和平局 `````````````````` 如何判断为平局。最多循环 5 轮，当第 4 轮之后，计算机就要跳出 **判断是否存在棋子的循环** ，然后再来个判断，用户出现三种情况之一，赢、输或者是平局。 判断输赢分两种情况，棋子 O 赢了，赋值 ``true`` 给变量 ``win_o`` （初始值为 ``false`` ），同样地，棋子 X 赢了，赋值 ``true`` 给变量 ``win_x`` （初始值为 ``false`` ） .. code-block:: c++ // 判断输赢 bool win_o = false, win_x = false; 接下来分别进行两次判断输赢，一次是判断用户，另一次是判断计算机 .. code-block:: c++ // 判断用户是否赢了 // 判断交叉线是否相等 if (mark[0][0] == " O " && mark [1][1] == " O " && mark[2][2] == " O " ) win_o = true; if (mark[0][0] == " X " && mark [1][1] == " X " && mark[2][2] == " X " ) win_x = true; if (mark[0][2] == " O " && mark [1][1] == " O " && mark[2][0] == " O " ) win_o = true; if (mark[0][2] == " X " && mark [1][1] == " X " && mark[2][0] == " X " ) win_x = true; // 判断横竖线是否相等 for (int c = 0; c < 3; ++c) { if (mark[c][0] == " O " && mark[c][1] == " O " && mark[c][2] == " O " ) win_o = true; if (mark[c][0] == " X " && mark[c][1] == " X " && mark[c][2] == " X " ) win_x = true; if (mark[0][c] == " O " && mark[1][c] == " O " && mark[2][c] == " O " ) win_o = true; if (mark[0][c] == " X " && mark[1][c] == " X " && mark[2][c] == " X " ) win_x = true; } if (win_x != true && win_o != true) // 如果用户没有赢，才轮到计算机下棋 { if (piece == "O") // 计算机选择的棋子要跟用户的不一样 mark[x][y] = " X "; else mark[x][y] = " O "; } // 判断计算机下棋时是否赢了 // 判断交叉线是否相等 if (mark[0][0] == " O " && mark [1][1] == " O " && mark[2][2] == " O " ) win_o = true; if (mark[0][0] == " X " && mark [1][1] == " X " && mark[2][2] == " X " ) win_x = true; if (mark[0][2] == " O " && mark [1][1] == " O " && mark[2][0] == " O " ) win_o = true; if (mark[0][2] == " X " && mark [1][1] == " X " && mark[2][0] == " X " ) win_x = true; // 判断横竖线是否相等 for (int c = 0; c < 3; ++c) { if (mark[c][0] == " O " && mark[c][1] == " O " && mark[c][2] == " O " ) win_o = true; if (mark[c][0] == " X " && mark[c][1] == " X " && mark[c][2] == " X " ) win_x = true; if (mark[0][c] == " O " && mark[1][c] == " O " && mark[2][c] == " O " ) win_o = true; if (mark[0][c] == " X " && mark[1][c] == " X " && mark[2][c] == " X " ) win_x = true; } // 输出每一步下棋的棋盘状态 string bar[3] ; // 定义间隔的竖线 for (int k = 0; k < 3; ++k) { bar[k] = '|' + mark[k][0] + '|' + mark[k][1] + '|' + mark[k][2] + '|' ; } cout << endl; cout << split_line << boundary << endl; cout << " 第 " << bar[0] << endl; cout << sidebar << boundary << endl; cout << " " << step << " " << bar[1] << endl; cout << sidebar << boundary << endl; cout << " 轮 " << bar[2] << endl; cout << split_line << boundary << endl; cout << endl; if (win_o || win_x) // 当满足棋子 O 或者 X 赢了的时候 { // 再判断是用户赢了还是计算机赢了 if ( (win_o && piece == "O") || (win_x && piece == "X") ) cout << " 你赢了 ^_^ \n" << endl; else cout << " 你输了 >_< \n" << endl; break; // 跳出循环，结束游戏 } if (i == 4) // 判断是否平局 { cout << " 平局 －_－# \n" << endl; break; // 跳出循环，结束游戏 } 3.7 本阶段完整代码 ``````````````````` 完整代码位于 ``/doc/sample/3.1.cpp`` `在线浏览 `_ 3.8 Bug ````````````` .. image:: bug.png