如何在 Python 中禁止数字输入中的字母输入？

Question

import datetime

now = datetime.datetime.now()

current_year = now.year

while True:

    user_name = str(input('What is your name?'))

    if user_name.isalpha():

        break

    else:
        print('Invalid input. Make sure to enter your name.')

        continue

while True:

    user_age = input('How old are you?')

    if user_age.isdigit():

        break

    else:

        print("Invalid input. Make sure to enter a number for your age.")

        continue

birth_year = (now.year - ***user_age***)

greeting = f"Hello {user_name}! You were born in {birth_year}."

print(greeting)

当我以这种方式编码时，当我尝试从

user_age

中减去

now.year

时，会出现错误。

TypeError: unsupported operand type(s) for -: 'int' and 'str'

。在尝试使用 while True 循环之前，代码运行良好。程序告诉用户出生年份和年龄。如果我将 int 放在输入前面，则会在

isdigit

上出现错误。感谢您的帮助。

Answer 1

与其尝试通过检查字符串来确定字符串是否可以转换为 int，不如尝试将其转换并管理可能出现的任何异常。

为此目的拥有一个可重用的函数很有用。

这是一个例子：

def getint(prompt):
    while True:
        x = input(prompt)
        try:
            return int(x)
        except ValueError:
            print(f"{x} is not a valid integer")

print(getint("How old are you? "))