檢查字符是否在字符串Python中

Question

from decimal import *
errors = "abcdffghijklmnopqrstuvwxyz?><:;\|{}[]"
purchase_price = Decimal(input("Please enter the price of your item"))
while purchase_price in errors:
    print("Please enter the price of your item ex: 123.45")
    break
else:

我在檢查是否輸入了錯誤var中的一個或多個字符時遇到麻煩。

當輸入的內容不是數字時

輸出為：

Traceback (most recent call last):
  File "C:/Users/Chris/PycharmProjects/Tax Calculator/main.py", line 4, in <module>
    purchase_price = Decimal(input("Please enter the price of your item"))
decimal.InvalidOperation: [<class 'decimal.ConversionSyntax'>]

如果有角色，我想編寫一個循環，使他們有另一個機會重新輸入價格。

Answer 1

如果希望輸入為數字，建議將其設為浮點型，並在無法解析的情況下處理異常：

try:
    purchase_price = float(input("Please enter the price of your item"))
except (ValueError, TypeError) as e:
    pass # wasn't valid, print an error and ask them again.

不過，請注意，浮動匯率並不是准確處理資金的好方法！ 這是一筆大買賣！ 您需要在線搜索以找到一個好的解決方案： http : //code.google.com/p/python-money/

Answer 2

from decimal import *

def ask():
    input_str = input("Please enter the price of your item");
    try:
        number = Decimal( imput_str )
        return number
    except( InvalidOperation, ValueError, TypeError ) as e:
        return ask()


number = ask()