Outdated

In the United States, dates are typically formatted in month-day-year order (MM/DD/YYYY), otherwise known as middle-endian order, which is arguably bad design. Dates in that format can’t be easily sorted because the date’s year comes last instead of first. Try sorting, for instance, 2/2/1800, 3/3/1900, and 1/1/2000 chronologically in any program (e.g., a spreadsheet). Dates in that format are also ambiguous. Harvard was founded on September 8, 1636, but 9/8/1636 could also be interpreted as August 9, 1636!

Fortunately, computers tend to use ISO 8601, an international standard that prescribes that dates should be formatted in year-month-day (YYYY-MM-DD) order, no matter the country, formatting years with four digits, months with two digits, and days with two digits, “padding” each with leading zeroes as needed.

In a file called outdated.py, implement a program that prompts the user for a date, anno Domini, in month-day-year order, formatted like 9/8/1636 or September 8, 1636, wherein the month in the latter might be any of the values in the list below:

[
    "January",
    "February",
    "March",
    "April",
    "May",
    "June",
    "July",
    "August",
    "September",
    "October",
    "November",
    "December"
]

Then output that same date in YYYY-MM-DD format. If the user’s input is not a valid date in either format, prompt the user again. Assume that every month has no more than 31 days; no need to validate whether a month has 28, 29, 30, or 31 days.

Hints

Recall that a str comes with quite a few methods, per docs.python.org/3/library/stdtypes.html#string-methods, including split.
Recall that a list comes with quite a few methods, per docs.python.org/3/tutorial/datastructures.html#more-on-lists, among which is index.
Note that you can format an int with leading zeroes with code like
```
print(f"{n:02}")
```
wherein, if n is a single digit, it will be prefixed with one 0, per docs.python.org/3/library/string.html#format-string-syntax.

Demo

Before You Begin

Log into cs50.dev, click on your terminal window, and execute cd by itself. You should find that your terminal window’s prompt resembles the below:

Next execute

mkdir outdated

to make a folder called outdated in your codespace.

Then execute

cd outdated

to change directories into that folder. You should now see your terminal prompt as outdated/ $. You can now execute

code outdated.py

to make a file called outdated.py where you’ll write your program.

How to Test

Here’s how to test your code manually:

Run your program with python outdated.py. Type 9/8/1636 and press Enter. Your program should output:
```
1636-09-08
```
Run your program with python outdated.py. Type September 8, 1636 and press Enter. Your program should output:
```
1636-09-08
```
Run your program with python outdated.py. Type 23/6/1912 and press Enter. Your program should reprompt the user.
Run your program with python outdated.py. Type December 80, 1980 and press Enter. Your program should reprompt the user.

You can execute the below to check your code using check50, a program that CS50 will use to test your code when you submit. But be sure to test it yourself as well!

check50 cs50/problems/2022/python/outdated

Green smilies mean your program has passed a test! Red frownies will indicate your program output something unexpected. Visit the URL that check50 outputs to see the input check50 handed to your program, what output it expected, and what output your program actually gave.

How to Submit

In your terminal, execute the below to submit your work.

submit50 cs50/problems/2022/python/outdated