Question

跟随Al Sweigarts的python课程，并尝试对他的cat代码进行一些修改。我可以使用if和elif语句输入“ ValueError除外”，但是我认为使用while语句会使事情搞砸。我希望当用户输入的内容不正确时可以重复执行此简单代码，到目前为止，该功能仍然有效。我只需要输入一个非整数地址作为输入即可。

是否与不使用break / continue语句有关？

print('How many cats do you got')
numCats = int(input())

while numCats < 0:
    print('That is not a valid number')
    print('How many cats do you got')
    numCats = int(input())

if numCats >= 4:
        print('That is a lot of cats')

elif numCats < 4:
    print('That is not a lot of cats')

except ValueError:
    print('That was not a valid number')

如果输入一个无效数字，我希望代码重复执行，同时在非整数值之后重复执行。但是，我无法超越ValueError部分。谢谢！

Answer 1

except块需要一个try块。在try块中，您可以找到异常，并且如果找到，则运行except子句。

while True:
    try:        
        print('How many cats do you got: ')
        numCats = int(input())
        if numCats >= 0:
            break
        else:
            print('That was not a valid number')
    except ValueError:
        print('That was not a valid number')

if numCats >= 4:
    print('That is a lot of cats')

elif numCats < 4:
    print('That is not a lot of cats')

找出ValueValue除外

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