Question

尝试为格式为YYYY-MM-DD的日期创建输入验证。我有两种方法可以做到这一点。

第一种方法似乎有效，并且每次出现错误时都会循环返回以获取输入。

第二种方法中的函数导致无限循环，但第一种方法中几乎相同的函数不会。

如果我在第二种方法中输入了正确格式的日期，它将按预期进行打印，但是对于其他任何输入，都会创建无限循环。

我不确定这在哪里分解？

我已经查看了许多Google搜索结果，并且有很多日期验证，但我还没有找到一个明确地解决如何环回并重试的验证。

我不确定在不重写方法一的情况下还要尝试什么。


import datetime as dt

#METHOD 1 - This is the first method for validating date input, which takes in individual blocks and validates each one individually. 

def get_date(year_prompt, month_prompt, day_prompt):

    #Year Input
    while True:
        try:
            year = int(input(year_prompt))
        except ValueError:
            print("Sorry, I didn't understand that.\n")
            continue
        if year in range(2000,3000,1):
            break
        else:
            print("Sorry, your response must be in YYYY format and later than the year 2000.\n")
            continue

    #Month Input
    while True:
        try:
            month = int(input(month_prompt))
        except ValueError:
            print("Sorry, I didn't understand that.\n")
            continue
        if month in range(1,13,1):
            break
        else:
            print("Sorry, needs to be MM and between 1-12\n")
            continue

    #Day Input
    while True:
        try:
            day = int(input(day_prompt))
        except ValueError:
            print("Sorry, I didn't understand that.\n")
            continue
        if day in range(1,32,1):
            break
        else:
            print("Sorry, needs to be DD and between 1-31\n")
            continue

    #Takes the three inputs and puts them together into a date
    date = dt.datetime(year, month, day)

    #Returns the date      
    return date

#Runs the first method of getting and validating a date.
date = get_date("\nYYYY: ", "\nMM: ", "\nDD: ")

#Prints the validated date.
print("\nThe date you entered is: ", date, "\n")


#METHOD 2 - This is the second method for validating date, which takes in the whole date in one input, and attempts to validate it against the YYYY-MM-DD format.

def input_validation(date):
    while True:
        try:
            dt.datetime.strptime(date, '%Y-%m-%d')
            break
        except ValueError:
            print("\nSorry, this does not appear to be a valid date in format YYYY-MM-DD")
            continue        
    return date

#Prints the validated date. 
print("\nThe date you entered is: ", input_validation(input("Enter a date in format YYYY-MM-DD: ")), "\n")

我对第二种方法的预期结果是格式为YYYY-MM-DD的日期，或者是错误消息，然后再次要求输入。

Answer 1

您可以摆脱无限循环while True，然后根据正确格式的日期返回True或False

def input_validation(date):

    #Flag to check date format
    flag = False
    try:
        #If date is of correct format, set flag to True
        dt.datetime.strptime(date, '%Y-%m-%d')
        flag = True
    except ValueError:
        print("\nSorry, this does not appear to be a valid date in format YYYY-MM-DD")
    #Return flag
    return flag

print(input_validation('2019-01-31'))
print(input_validation('2019-001-31'))
print(input_validation('2019-01-311'))

输出将为

True

Sorry, this does not appear to be a valid date in format YYYY-MM-DD
False

Sorry, this does not appear to be a valid date in format YYYY-MM-DD
False

您可以将此功能包装在while True周围，以继续接受用户的输入

while True:
    date_str = input('Enter Date')
    if input_validation(date_str):
        break

为一个函数获取一个无限循环，但没有为一个类似函数获取一个无限循环，试图验证日期输入

1 个答案: