0

函数 break 和 pass 似乎无法在正确的输入下工作，程序停止，如果没有正确的输入，程序决定不中断而是打印字符串，告诉用户存在问题并继续运行。

currency = str(raw_input ("""what currency would you like to covert: GBP, EURO, USD OR YEN?
"""))


exchange = str(raw_input("""what currency would you like in exchange? : GBP, EURO, USD OR YEN?
                              """))

amount = int(input("""how much would you like to convert?
                      """))



valid_input = ('EUR','eur','GBP','gbp' ,'USD','usd','JPY','jpy')

while True:

    if currency in valid_input and exchange in valid_input:

        pass

    else:

        print("incorrect input, please restart program")
        break


decision = str(raw_input("""Please enter u for user input exchange rate or s for the preset exchange rate
    """))


if decision == "u" :
    user_rate = raw_input("Please enter the current exchange rate")

    exchange_value = int(amount) *  int(user_rate)

    print ("At the user found exchange rate you will receive",exchange_value,exchange)



    elif decision == "s" :


    if currency  == "GBP" and exchange == "USD":

        exchange_value= int(amount) * 1.6048

        print ("At the preset exchange rate you will receive",exchange_value,exchange)

    if currency  == "GBP" and exchange == "EUR":

        exchange_value= int(amount) * 1.2399

        print ("At the preset exchange rate you will receive",exchange_value,exchange)
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2 回答 2

1

您的break语句跳出循环，继续执行程序的其余部分。如果您想退出程序，请使用类似sys.exit.

pass什么都不做；它是一个空块的占位符。当您使用它时，它基本上会导致您的循环永远循环。那是你打算使用的地方break。

于 2013-05-12T09:46:36.863 回答
-2

"break" 仅适用于 switch 和 for/while

于 2013-05-12T09:39:57.783 回答