掷骰子游戏做while循环不满足退出条件

Posted 2023-02-22

【中文标题】掷骰子游戏做while循环不满足退出条件

【英文标题】：Game of Craps do while loop not meeting exit condition

【发布时间】：2019-10-29 15:59:24

【问题描述】：

我正在尝试使用 C++ 模拟掷骰子游戏，其中对游戏进行多次迭代，并记录每场游戏的每场胜利、失败和掷骰数。

每场比赛的规则：

掷 2 个骰子并将结果相加。 2、3 或 12 = 输（1 卷），7 或 11 = 赢（1 卷）。如果两者都没有，则再次掷骰子，直到玩家掷出 7（输）或再次掷出原来的分数（赢）。

#include<iostream>
#include<cstdlib>
#include<ctime>
#include<vector>    // Allows use of vectors

double random();    // Returns random double between 0 and 1
int dice(double x); // Converts a double between 0 and 1 into an int between 1 and 6
int two_dice(int die_one, int die_two); // Sums 2 ints together, in this case dice rolls


int main()

    // Sets the seed for rand using the current time, i.e. rand() 
    // will now always generate from a different starting point 
    std::srand(std::time(nullptr));

    // Vectors to store the results of win/lose
    std::vector<int> won;
    std::vector<int> lose;

    for (int i = 0; i < 10; i++)
    
        int num_throws = 1;

        // Roll two dice
        double x = random(), y = random();
        int die_one = dice(x);
        int die_two = dice(y);
        int roll = two_dice(die_one, die_two);

        std::cout << "\nRoll " << i + 1 << " = " << roll << "\n";

        if (roll < 4 || roll == 12)   // Instant loss
        
            lose.push_back(num_throws);
        
        else if (roll == 7 || roll == 11)     // Instant win
        
            won.push_back(num_throws);
        
        else     // Begin looping rolls until a 7 or original roll is rolled again
        
            int point = roll;     // First roll 
            std::cout << "Point is " << point << "\n";

            do 
                num_throws++;     
                double x = random(), y = random();
                int die_one = dice(x);
                int die_two = dice(y);
                int roll = two_dice(die_one, die_two);     // Roll dice again
                std::cout << "Next roll = " << roll << "\n";
                std::cout << "Point is " << point << "\n";
             while (roll != 7 || roll != point);

            if (roll == 7)
            
                lose.push_back(num_throws);
                std::cout << "lose\n";
            
            else if (roll == point)
            
                won.push_back(num_throws);
                std::cout << "win\n";
            
            else
            
                std::cout << "\n\nERROR\n\n";
            

            std::cout << "Number of throws was " << num_throws << "\n";
        
    

    std::cout << "Number of throws for each win:\n";
    for (auto i: won)
        std::cout << i << "\n";

    std::cout << "\nNumber of throws for each lose:\n";
    for (auto i : lose)
        std::cout << i << "\n";

    return 0;


double random() // Returns random double between 0 and 1

    double rand_num = rand() % 1000 + 1;
    return rand_num / 1000;


int dice(double x)  // Converts a double between 0 and 1 into an int between 1 and 6

    double dice_roll = (x * 6) + 1;
    return dice_roll;


int two_dice(int die_one, int die_two)  // Sums 2 ints together, in this case dice rolls

    return die_one + die_two;

在运行代码时，do-while 循环退出条件永远不会满足，即使滚动实际上 = 7 或点也是如此。它只是不断循环。我也尝试将 int 点更改为 const int 点，但都不起作用。有谁知道为什么会这样？

我知道这可能被过度评论了，但这是为了任何人都可以快速尝试阅读代码，并且我已经包含了很多打印语句，所以你最好尝试找出什么不起作用。

编辑：我的问题已经解决了，谢谢大家的回答！

【问题讨论】：

试着想一个数字会导致，例如，roll != 7 || roll != 9 为假。

试试while(roll != 7 && roll != point);

当我使用 && 时，它会立即退出循环，即执行 do 部分但随后退出而不管结果。

【参考方案1】：

问题出在while (roll != 7 || roll != point);这一行。

假设points不等于7；如果 roll 等于 7，则 roll != points 评估为 true，因此循环继续。反之亦然，如果roll == points 则roll != 7 为真，循环继续。

既然你在while循环之后测试结果，我建议使用breakstatement：

do 
    num_throws++;     
    double x = random(), y = random();
    int die_one = dice(x);
    int die_two = dice(y);
    int roll = two_dice(die_one, die_two);     // Roll dice again
    std::cout << "Next roll = " << roll << "\n";
    std::cout << "Point is " << point << "\n";
    if (roll == 7)
    
        lose.push_back(num_throws);
        std::cout << "lose\n";
        break;
    
    else if (roll == point)
    
        won.push_back(num_throws);
        std::cout << "win\n";
        break;
    
 while (true);