Credit

Problem to Solve

In a filed called credit.py in a folder called sentimental-credit, write a program that prompts the user for a credit card number and then reports (via print) whether it is a valid American Express, MasterCard, or Visa card number, exactly as you did in Problem Set 1. Your program this time should be written in Python!

Demo

Specification

So that we can automate some tests of your code, we ask that your program’s last line of output be AMEX\n or MASTERCARD\n or VISA\n or INVALID\n, nothing more, nothing less.
For simplicity, you may assume that the user’s input will be entirely numeric (i.e., devoid of hyphens, as might be printed on an actual card).
Best to use get_int or get_string from CS50’s library to get users’ input, depending on how you to decide to implement this one.

Hints

It’s possible to use regular expressions to validate user input. You might use Python’s re module, for example, to check whether the user’s input is indeed a sequence of digits of the correct length.

How to Test

While check50 is available for this problem, you’re encouraged to first test your code on your own for each of the following.

Run your program as python credit.py, and wait for a prompt for input. Type in 378282246310005 and press enter. Your program should output AMEX.
Run your program as python credit.py, and wait for a prompt for input. Type in 371449635398431 and press enter. Your program should output AMEX.
Run your program as python credit.py, and wait for a prompt for input. Type in 5555555555554444 and press enter. Your program should output MASTERCARD.
Run your program as python credit.py, and wait for a prompt for input. Type in 5105105105105100 and press enter. Your program should output MASTERCARD.
Run your program as python credit.py, and wait for a prompt for input. Type in 4111111111111111 and press enter. Your program should output VISA.
Run your program as python credit.py, and wait for a prompt for input. Type in 4012888888881881 and press enter. Your program should output VISA.
Run your program as python credit.py, and wait for a prompt for input. Type in 1234567890 and press enter. Your program should output INVALID.

Correctness

check50 cs50/problems/2024/fall/sentimental/credit

Style

style50 credit.py

How to Submit

Per Step 4 below, after you submit, be sure to check your autograder results. If you see SUBMISSION ERROR: missing files (0.0/1.0), it means your file was not named exactly as prescribed (or you uploaded it to the wrong problem).

Correctness in submissions entails everything from reading the specification, writing code that is compliant with it, and submitting files with the correct name. If you see this error, you should resubmit right away, making sure your submission is fully compliant with the specification. The staff will not adjust your filenames for you after the fact!

Download your credit.py file by control-clicking or right-clicking on the file in your codespace’s file browser and choosing Download.
Go to CS50’s Gradescope page.
Click Problem Set 6: Sentimental (Credit).
Drag and drop your credit.py file to the area that says Drag & Drop. Be sure it has that exact filename! If you upload a file with a different name, the autograder likely will fail when trying to run it. Ensuring you have uploaded files with the correct filename is your responsibility!
Click Upload.

You should see a message that says “Problem Set 6: Sentimental (Credit) submitted successfully!”