heartland-mask

Your mission

Copy a card number into out with everything but the last four characters starred over.

today's brief

2008. Albert Gonzalez and his crew push SQL injection into Heartland Payment Systems and sit on the network for months, sniffing card numbers off the wire as they cross it in the clear. About 130 million cards. Heartland was processing for 175,000 merchants and heard about it from Visa, in January, after the fact. Write the numbers the way the receipts should have.

See it in action

mask_pan(out, "4111111111111111", 16)

Expected result

************1111

Your checklist

For your own tracking. Tests grade your code.

pan is a card number of n characters, and out has room for n characters and a terminator.
Write into out the same number with every character except the last four replaced by a star, then terminate it.
A number of four characters or fewer goes across unchanged.

More examples

mask_pan(out, "12345", 5)

Expected result

*2345

mask_pan(out, "1234", 4)

Expected result

Constraints

Expected files

mask.c

Allowed functions

None. Write every helper yourself.

Back to compete

Solutions

heartland-mask

Your mission

Copy a card number into out with everything but the last four characters starred over.

today's brief

See it in action

mask_pan(out, "4111111111111111", 16)

Expected result

************1111

Your checklist

For your own tracking. Tests grade your code.

pan is a card number of n characters, and out has room for n characters and a terminator.
Write into out the same number with every character except the last four replaced by a star, then terminate it.
A number of four characters or fewer goes across unchanged.

More examples

mask_pan(out, "12345", 5)

Expected result

*2345

mask_pan(out, "1234", 4)

Expected result

Constraints

Expected files

mask.c

Allowed functions

None. Write every helper yourself.

Back to compete

Solutions