如何检查字符串输入是否为数字?

问题描述：

如何检查用户的字符串输入是否为数字(例如-1，0，1等)?

How do I check if a user's string input is a number (e.g. -1, 0, 1, etc.)?

user_input = input("Enter something:")

if type(user_input) == int:
    print("Is a number")
else:
    print("Not a number")

由于input始终返回字符串，因此上述方法无效.

The above won't work since input always returns a string.

答

简单地尝试将其转换为int，然后在不起作用时进行补救.

Simply try converting it to an int and then bailing out if it doesn't work.

try:
   val = int(userInput)
except ValueError:
   print("That's not an int!")