通过验证简单输入进行异常处理

Question

我是 Python 的新手，在我设法学习 Java 之后达到了高级水平。在 Java 中，使用异常处理进行输入验证对我来说从来都不是问题，但在 python 中，我有点困惑：

这是一个简单的 FizzBuzz 程序示例，它只能读取 0 到 99 之间的数字，否则必须抛出异常：

if __name__ == '__main__':

def fizzbuzz(n):
    try:
        if(0<= n <= 99):
            for i in range(n):
                if i==0:
                    print("0")
                elif (i%3==0 and i%7==0) :
                    print("fizzbuzz")
                elif i%3==0:
                    print("fizz")
                elif i%7==0:
                    print("buzz")
                else:
                    print(i)    
    except Exception:
        print("/// ATTENTION:The number you entered was not in between 0 and 99///")   

try:
    enteredNumber = int(input("Please enter a number in between 0 and 99: "))
    fizzbuzz(enteredNumber)
except Exception:
    print("/// ATTENTION: Something went wrong here. Next time, try to enter a valid Integer ////")

如果我运行并输入例如123 代码刚刚终止，没有任何反应。

Answer 1

如果你想捕捉异常，你需要确保它会在期望的场景发生时被引发。

由于try和except之间的代码块本身不会引发异常，所以需要自己引发一个：

try:
    if(0<= n <= 99):
        ... 
    else:
        raise Exception()
except Exception:
    ...

Answer 2

当您的条件不满足时，您需要从 fizzbuzz() 引发异常。尝试以下：

if __name__ == '__main__':

def fizzbuzz(n):
    try:
        if(0<= n <= 99):
            for i in range(n):
                if i==0:
                    print("0")
                elif (i%3==0 and i%7==0) :
                    print("fizzbuzz")
                elif i%3==0:
                    print("fizz")
                elif i%7==0:
                    print("buzz")
                else:
                    print(i) 
        else:
            raise ValueError("Your exception message")
    except Exception:
        print("/// ATTENTION:The number you entered was not in between 0 and 99///")   

try:
    enteredNumber = int(input("Please enter a number in between 0 and 99: "))
    fizzbuzz(enteredNumber)
except Exception:
    print("/// ATTENTION: Something went wrong here. Next time, try to enter a valid Integer ////")

此外，您必须捕获特定异常而不是捕获一般异常。

通过验证简单输入进行异常处理

Exception Handling by validating simple inputs

python

validation

exception-handling