JeanExtreme002

问题是您没有创建 Arithmetic 在调用方法之前。因为您没有创建对象,所以不会向 self 参数。这会导致消息 "Enter your first number:" 传递给 自己 参数和 msg 参数为空。

要解决此问题,只需在类名后面使用括号创建一个对象,例如:

# Declare variables. Ask user for input and use the exception handling function       
n1 = Arithmetic().float_input("Enter your First number: ")
n2 = Arithmetic().float_input("Enter your Second number: ")

如果不是故意创建对象,则可以使用 @classmethod 类装饰器将类名传递给 自己 参数。

# Define class

class Arithmetic:

    @classmethod
    def float_input(class_, msg): # Use this function for exception handling during user input

        while True:
            try:
                return float(input(msg))
            except ValueError:
                print("You must enter a number!")
            else:
                break
    # Code...

n1 = Arithmetic.float_input("Enter your First number: ")
n2 = Arithmetic.float_input("Enter your Second number: ")

还有一个名为 @staticmethod . 如果使用此装饰器,则可以调用该方法,而不必具有 算术 不用定义 自己 在方法签名中。例子:

class Arithmetic:

    @staticmethod
    def float_input(msg): # Use this function for exception handling during user input
        while True:
            try:
                return float(input(msg))
            except ValueError:
                print("You must enter a number!")
            else:
                break
    # Code...

n1 = Arithmetic.float_input("Enter your First number: ")
n2 = Arithmetic.float_input("Enter your Second number: ")