防止用户在 Python 3 中输入字符串

Question

我是用 Python 3 写的，但是如何防止用户输入字符串呢？x = int(input("If you want to play with computer, click 0. If you want to play with your friend, click 1. "))

Answer 1

使用try/except

while True:

    user_input = input("If you want to play with computer, click 0. If you want to play with your friend, click 1. ")

    try:

        user_input = int(user_input)

        # do something

        break

    except ValueError:

        print("input a valid choice please")

Answer 2

您可以在整数转换之前添加一个带有 typeisnumeric方法的if 语句，如下所示：str

x = input('Enter a number: ')

if x.isnumeric(): # Returns True if x is numeric, otherwise False.

    int(x) # Cast it and do what you want with it.

else: # x isn't numeric

    print('You broke the rules, only numeric is accepted.')