PROBLEM2.4.md

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Vanity Plates

In Massachusetts, home to Harvard University, it’s possible to request a vanity license plate for your car, with your choice of letters and numbers instead of random ones. Among the requirements, though, are:

• “All vanity plates must start with at least two letters.”
• “… vanity plates may contain a maximum of 6 characters (letters or numbers) and a minimum of 2 characters.”
• “Numbers cannot be used in the middle of a plate; they must come at the end. For example, AAA222 would be an acceptable … vanity plate; AAA22A would not be acceptable. The first number used cannot be a ‘0’.”
• “No periods, spaces, or punctuation marks are allowed.”

In plates.py, implement a program that prompts the user for a vanity plate and then output Valid if meets all of the requirements or Invalid if it does not. Assume that any letters in the user’s input will be uppercase. Structure your program per the below, wherein is_valid returns True if s meets all requirements and False if it does not. Assume that s will be a str. You’re welcome to implement additional functions for is_valid to call (e.g., one function per requirement).

	def main():
		plate = input("Plate: ")
		if is_valid(plate):
			print("Valid")
		else:
			print("Invalid")


	def is_valid(s):
		...


	main()

Hints

• Recall that a str comes with quite a few methods, per docs.python.org/3/library/stdtypes.html#string-methods.
• Much like a list, a str is a “sequence” (of characters), which means it can be “sliced” into shorter strings with syntax like s[i:j]. For instance, if s is "CS50", then s[0:2] would be "CS".

Before You Begin

From the root of your repository execute cd 2-Loops So your current working directory is ...

	/2-Loops $:

Next execute

	mkdir plates

to make a folder called plates in your codespace.

Then execute

	cd plates

to change directories into that folder. You should now see your terminal prompt as /2-Loops/plates $. You can now execute

	code plates.py

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

How to Test

Here’s how to test your code manually:

1. Run your program with python plates.py. Type CS50 and press Enter. Your program should output:

    Valid

2. Run your program with python plates.py. Type CS05 and press Enter. Your program should output:

    Invalid

3. Run your program with python plates.py. Type CS50P and press Enter. Your program should output

    Invalid

4. Run your program with python plates.py. Type PI3.14 and press Enter. Your program should output

    Invalid

5. Run your program with python plates.py. Type H and press Enter. Your program should output

    Invalid

6. Run your program with python plates.py. Type OUTATIME and press Enter. Your program should output

    Invalid

Commit your program to GITHUB

At the /2-Loops/plates $ prompt in your terminal:

	git add -A 

Add all changed files in the repository to be committed

	git commit -m “Upload completed plates.py“

Commit all changes in the REPO with the comment “Upload completed plates.py“ note: If the file is not complete, adjust the comment to describes what is being commited

	git push 

Push all changes to the REPO