Credit
Implement a program that determines whether a provided credit card number is valid according to Luhn’s algorithm.
$ python credit.py
Number: 378282246310005
AMEX
Getting Started
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
wget https://cdn.cs50.net/2022/fall/psets/6/sentimental-credit.zip
in order to download a ZIP called sentimental-credit.zip
into your codespace.
Then execute
unzip sentimental-credit.zip
to create a folder called sentimental-credit
. You no longer need the ZIP file, so you can execute
rm sentimental-credit.zip
and respond with “y” followed by Enter at the prompt to remove the ZIP file you downloaded.
Now type
cd sentimental-credit
followed by Enter to move yourself into (i.e., open) that directory. Your prompt should now resemble the below.
sentimental-credit/ $
Execute ls
by itself, and you should see credit.py
. If you run into any trouble, follow these same steps again and see if you can determine where you went wrong!
Specification
- In
credit.py
, write a program that prompts the user for a credit card number and then reports (viaprint
) whether it is a valid American Express, MasterCard, or Visa card number, exactly as you did in Problem Set 1, except that your program this time should be written in Python. - So that we can automate some tests of your code, we ask that your program’s last line of output be
AMEX\n
orMASTERCARD\n
orVISA\n
orINVALID\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
orget_string
from CS50’s library to get users’ input, depending on how you to decide to implement this one.
Usage
Your program should behave per the example below.
$ python credit.py
Number: 378282246310005
AMEX
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.
Testing
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 in378282246310005
and press enter. Your program should outputAMEX
. - Run your program as
python credit.py
, and wait for a prompt for input. Type in371449635398431
and press enter. Your program should outputAMEX
. - Run your program as
python credit.py
, and wait for a prompt for input. Type in5555555555554444
and press enter. Your program should outputMASTERCARD
. - Run your program as
python credit.py
, and wait for a prompt for input. Type in5105105105105100
and press enter. Your program should outputMASTERCARD
. - Run your program as
python credit.py
, and wait for a prompt for input. Type in4111111111111111
and press enter. Your program should outputVISA
. - Run your program as
python credit.py
, and wait for a prompt for input. Type in4012888888881881
and press enter. Your program should outputVISA
. - Run your program as
python credit.py
, and wait for a prompt for input. Type in1234567890
and press enter. Your program should outputINVALID
.
Execute the below to evaluate the correctness of your code using check50
. But be sure to compile and test it yourself as well!
check50 cs50/problems/2023/x/sentimental/credit
Execute the below to evaluate the style of your code using style50
.
style50 credit.py
How to Submit
In your terminal, execute the below to submit your work.
submit50 cs50/problems/2023/x/sentimental/credit