python - 如何在python中使用带有输入的比较符号

Question

我正在尝试制作一个可以响应某人年龄的程序，但我不知道如何使用比较符号。这是我试图运行的代码，

age = input('How old are you? \n >>')
if (age < 20):
    print('Hey you are pretty young.')
if (age > 20):
    print('wow you are pretty old')

但是当我尝试运行它时，我收到此错误，

Traceback (most recent call last):
  File "C:/Users/Daniel/Desktop/Computer science/week 6/age.py", line 2, in <module>
    if (age < 20):
TypeError: '<' not supported between instances of 'str' and 'int'

Answer 1

你得到的输入是一个字符串，你需要将它转换为 int 才能比较它:

age = int(input('How old are you? \n >>'))

更好的是，添加一些错误处理，例如:

try:
    age = int(input('How old are you? \n >>'))

except ValueError as ex:
    print("Not a valid age.")