虽然循环不会在python中停止

Question

我们正在尝试制作一个 python 程序来模拟掷骰子游戏并显示获胜的概率。我已经缩小了while循环的答案，正如标题所示，当它到达循环时它不会退出。据我所知，循环应该退出，而只是返回和无休止的“假”列车。这是带有 cmets 的整个程序的代码，我将在底部输入掷骰子的规则（就我们在程序中使用的而言）。

import random
def craps()
    roll = random.randint(1,6) + random.randint(1,6)
if (roll == 7 or roll == 11): #Tests if the player should win. If so it adds a 1 to the win counter 
    return 1
elif (roll == 2 or roll == 3 or roll == 12): #Tests if player should lose. If so adds 0
    return 0
else:
    roll2 = 0 #initializes roll2 for the while
    while (roll2 != roll or roll2 != 7): #The player keeps rolling until they get a 7 or the initial roll
        roll2 == random.randint(1,6) + random.randint(1,6) #Rolls the dice
        if (roll2 == roll): #Tests if the player should win
            return 1
        elif (roll2 == 7): #Tests if the player should lose
            return 0

win = 0 #Start the win counter at 0
games = int(input("Enter the amount of games you want played: ")) #Accept how many games will be played
for i in range (games): 
    win = win + craps() #adds a 1 or a 0 depending on if a game was won

print ("The probability of winning is:", win, "/", games, " =", float(win)/games) #print the probability of winning

我们使用的基本规则是：玩家掷出 2 个六面骰子，如果初始掷出的是 7 或 11，则玩家获胜（第 4 行）。如果玩家掷出 2、3 或 12，则玩家输掉（第 6 行） 如果玩家没有得到任何结果，他们将继续滚动，直到与初始掷骰相符或掷出 7。如果与初始掷骰相符，则获胜，如果他们得到一个 7 他们输了（第 10-15 行）。我们的程序应该模拟并显示玩家获胜的概率。

这是我第一次使用这个网站，所以如果我将来搞砸了任何事情，请告诉我。感谢您的帮助！

Answer 1

一个常见但非常令人沮丧和浪费时间的拼写错误，即使是最优秀的 Python 开发人员也可能会遇到这种错误。将roll2 == random.randint(1,6) + random.randint(1,6) 替换为roll2 = random.randint(1,6) + random.randint(1,6)。

另外，我认为你需要roll2 != roll and roll2 != 7。从文体的角度来看，最好省略在 if 或 while 行中评估的语句周围的括号。

不过，您的循环中存在少量冗余。您在每个循环的顶部和每个循环的末尾检查 roll2 是否为 roll 或 7。你也可以考虑试试这个：

while True:
    # do everything in the same way as before

或

while roll2 != roll and roll2 != 7:
    # do stuff with the roll
    roll = random.randint(1,6) + random.randint(1,6)
return 1 if roll2 == roll else return 0 # a "ternary operator" in Python

Answer 2

双等号测试是否相等。将其更改为 single 以使您的代码正常工作。这是您编辑的代码：

import random
def craps()
    roll = random.randint(1,6) + random.randint(1,6)
if (roll == 7 or roll == 11): #Tests if the player should win. If so it adds a 1 to the win counter 
    return 1
elif (roll == 2 or roll == 3 or roll == 12): #Tests if player should lose. If so adds 0
    return 0
else:
    roll2 = 0 #initializes roll2 for the while
    while (roll2 != roll or roll2 != 7): #The player keeps rolling until they get a 7 or the initial roll
        roll2 = random.randint(1,6) + random.randint(1,6) #Rolls the dice
        if (roll2 == roll): #Tests if the player should win
            return 1
        elif (roll2 == 7): #Tests if the player should lose
            return 0

win = 0 #Start the win counter at 0
games = int(input("Enter the amount of games you want played: ")) #Accept how many games will be played
for i in range (games): 
    win = win + craps() #adds a 1 or a 0 depending on if a game was won

print ("The probability of winning is:", win, "/", games, " =", float(win)/games) #print the probability of winning

这是一个例子：

>>> import time
>>> x = 7
>>> x == 7
True
>>> while x != 6:
...     x == 6
...     time.sleep(1)
... 
False
False
False
^CTraceback (most recent call last):
  File "<stdin>", line 3, in <module>
KeyboardInterrupt
>>> while x != 6:
...     x = 6
...     time.sleep(1)
... 
>>> 

Answer 3

你的第一个问题是这一行：

while (roll2 != roll or roll2 != 7): #The player keeps rolling until they get a 7 or the initial roll

如果 roll 不等于 7，这将是一个无限循环。您应该在此处使用 and，因为如果其中 one 为 false，not 如果两者都是。有意义吗？

你想要：

while (roll2 != roll and roll2 != 7): #as long as both are not `True` then keep rolling.

你的另一个问题是这一行：

roll2 == random.randint(1,6) + random.randint(1,6) 

double equals 检查roll2 是否等于左边的表达式。您要做的是将其设置为等于左侧的表达式，如下所示：

roll2 = random.randint(1,6) + random.randint(1,6)