如何定义内部嵌套while循环与try-except结构的Python输入校验函数

原有代码的核心错误如下：

• 循环逻辑错误：while ValueError 直接用异常类作为循环判断条件，虽然恒为True可进入循环，但属于逻辑写法错误，应该通过是否获取到合法输入控制循环结束。
• 变量和内置函数使用错误：将Python内置的input函数作为参数传递、尝试为input()调用结果赋值的写法均不符合语法规则，且校验函数没有返回合法输入值，无法给后续业务逻辑使用。
• 异常捕获逻辑不完整：except分支中直接调用int(input())没有做二次异常捕获，只要第二次输入仍然非法就会直接抛出异常终止程序，无法实现循环校验效果。
• 业务逻辑变量赋值错误：原代码中times_table = input是将函数本身赋值给变量，而非获取用户输入结果，后续传入range函数时会直接抛出类型错误。

可复用输入校验函数 #

def trytrytryagain(prompt: str) -> int:
    while True:
        try:
            user_input = input(prompt)
            return int(user_input)
        except ValueError:
            print("You must enter a number")

修正后的完整乘法表代码 #

from time import sleep

def trytrytryagain(prompt: str) -> int:
    while True:
        try:
            user_input = input(prompt)
            return int(user_input)
        except ValueError:
            print("You must enter a number")

def validate_yes_no(prompt: str) -> str:
    while True:
        user_input = input(prompt).lower()
        if user_input in ("yes", "no"):
            return user_input
        print("You must enter either yes or no")

# 主业务逻辑
times_table = trytrytryagain("Please input the times table you wish to complete (1, 2, 3, etc.): ")
othertables = validate_yes_no("Would you like to go up to another times table (do the 1 to 12 times tables)? yes/no: ")

if othertables == "yes":
    other_times_table = trytrytryagain("Enter which time table you want to go up to: ")
    max_value = trytrytryagain("Enter the maximum table you would like to go up to. (if you do the 3 to 5 times tables, what times table would you like to finish on - type 12 for 5 x 12, 13 for 5 x 13, etc.): ")
    for x2 in range(times_table, other_times_table + 1):
        for x in range(max_value + 1):
            print(f"{x} x {x2} =")
            input()
            sleep(0.1)
else:
    print("Okay.")
    max_value = trytrytryagain("Enter the maximum table you would like to go up to. (if you do the 3 to 5 times tables, what times table would you like to finish on (type 12 for 5 x 12, etc.)): ")
    for x in range(times_table, max_value + 1):
        answer = x * times_table
        print(f"{x} times {times_table} is {answer}")
        sleep(0.1)

内容的提问来源于stack exchange，提问作者Zayn Merchant Dar