PYTHON：无法正确循环

Question

编辑：谢谢，问题已得到解答！

该程序运行正常，除了它不会循环以允许用户玩新游戏这一事实。即，在输入太多、太少或完美的更改量后，程序会询问“再试一次（y/n）？：”。但是我不知道为什么它不循环......而且当它循环时，它不需要包含关于解释游戏的大段。只是关于“输入加起来为“+str(number)+”美分的硬币，每行一个。”这一行。有什么建议吗？

#Setup

import random
playagain = "y"

#Main Loop

if (playagain == "y"):

    number = random.randint(1,99) #Generation of how many cents
    total = 0 #Running sum of guessed coins.

    print("The purpose of this exercise is to enter a number of coin values")
    print("that add up to a displayed target value. \n")
    print("Enter coins values as 1-penny, 5-nickel, 10-dime,and 25-quarter.")
    print("Hit return after the last entered coin value.\n")
    print("Enter coins that add up to "+str(number)+" cents, one per line.\n")

    while (True):
        if (total == 0):
            word = "first"
        else:
            word = "next"

        guess = str(input("Enter "+str(word)+" number: ")) #Records coin value

        #Entry Validation
        if (guess == ""): #When user is done guessing.
            if (total < number):
                print("Sorry - you only entered "+str(total)+" cents.\n")
                break
            elif (total > number):
                print("Sorry -  total amount exceeds "+str(number)+" cents.\n")
                break
            else:
                print("Correct!")
                break
        elif (int(guess) == 1) or (int(guess) == 5) or (int(guess) == 10) or (int(guess) == 25): 
            total = total + int(guess)        

        else:
            print("Invalid entry")
playagain = str(input("Try again (y/n)?: ")) #BRETT: I can't seem to get this to loop properly.

Answer 1

通过使用 break，您将完全退出 while 循环，并且永远不会检查 playagain 条件。如果您想查看用户是否想再次播放，请将“playagain”检查放在另一个 while 循环中。

#Setup

import random
playagain = "y"

#Main Loop

while (playagain == "y"):

    number = random.randint(1,99) #Generation of how many cents
    total = 0 #Running sum of guessed coins.

    print("The purpose of this exercise is to enter a number of coin values")
    print("that add up to a displayed target value. \n")
    print("Enter coins values as 1-penny, 5-nickel, 10-dime,and 25-quarter.")
    print("Hit return after the last entered coin value.\n")
    print("Enter coins that add up to "+str(number)+" cents, one per line.\n")

    while (True):
        if (total == 0):
            word = "first"
        else:
            word = "next"

        guess = str(input("Enter "+str(word)+" number: ")) #Records coin value

        #Entry Validation
        if (guess == ""): #When user is done guessing.
            if (total < number):
                print("Sorry - you only entered "+str(total)+" cents.\n")
                break
            elif (total > number):
                print("Sorry -  total amount exceeds "+str(number)+" cents.\n")
                break
            else:
                print("Correct!")
                break
        elif (int(guess) == 1) or (int(guess) == 5) or (int(guess) == 10) or (int(guess) == 25): 
            total = total + int(guess)        

        else:
            print("Invalid entry")
    playagain = str(input("Try again (y/n)?: ")) #BRETT: I can't seem to get this to loop properly.

Answer 2

您将playagain 设置为y/n，但如果playagain 等于“y”，则代码不会回到开头。尝试将if playagain == "y" 变成while playagain == "y"。这样，如果 playagain 仍然设置为“y”，它会经历第一次并继续回到开头。

另外，缩进最后一行 (playagain = str(....))，使其成为 while playagain == "y" 循环的一部分。如果不是，那么代码将陷入无限循环，因为在 while 循环内不会更改 playagain。

Answer 3

将最后一行缩进到while True 行。并将if (playagain == "y"): 更改为

while (playagain == "y"):

Answer 4

您的“主循环”不是循环，它只是一个 if 语句。此外，最好使用 raw_input，因为 input 会评估您的输入。尝试类似这样的方法：

playagain = 'y'
#Main loop
while playagain == 'y':
    print "do gamelogic here..."
    playagain = raw_input("Try again (y/n)?: ")

在您的游戏逻辑中，您可以使用布尔值来检查您是否需要打印游戏说明：

show_explanation = True
while playagain == 'y':
    if show_explanation:
        print "how to play is only shown once..."
        show_explanation = False

    print "Always do this part of the code"
    ...

    playagain = raw_input("Try again (y/n)?: ")