如何使用 Try 和 Exception 在 Python 中引发带有打印消息的错误？

Question

I'm trying to run a collatz in Python and I'm having trouble taking into account input that isn't an integer. I would like to have a Try and Except to work within my code that considers the user's non-integer input. Please see my code below.

number = int(input("Please enter a number: "))

def collatz(number):
    if number % 2 == 0:
        print(number // 2)
        return number // 2
    elif number % 2 == 1:
        print(number * 3 + 1)
        return number * 3 + 1

while number != 1:
    try:
        number = collatz(int(number))
    except ValueError:
        print("Something went wrong, please try again...")

Answer 1

You are not using the try except when you are calling int on the input, which is why it is still erroring. You should use 2 while loops like this:

number = input("Please enter a number: ")
while not number.isdigit():
    number = input("Please enter a number again: ")
number = int(number)

def collatz(number):
    if number % 2 == 0:
        print(number // 2)
        return number // 2
    elif number % 2 == 1:
        print(number * 3 + 1)
        return number * 3 + 1

With try-except (in this case don't include the initial stuff in the other solution):

while True:
    try:
        number = int(input("Please enter a number: "))
        break
    except:
        pass