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modular programming

Your coffee bar program still uses

the old format

Your program in the coffee bar was never updated after the health club
switched banks. It’s still doing what it always did: it’s still creating files
in the old format. So that‛s a donut.
Better write Credit
That old format wrote out the price and the credit card the other way Card... then Price...
round, which meant when your program wrote out a record like this: then Description.

Price = $1.50
The credit card number
Description

5079142874628151 0000150 DONUT

The new bank read the record like this:

Messed up credit card number:

The price... $50,791.42! the bank thought it was fake. But at least the
description's OK.

5079142 8746281510000150 DONUT

This is suspicious...
$50,000 for a donut....
Does not compute... Fake
credit card information!
Security! Security!!

So it’s not that somebody broke into your program and changed it.
No, it’s the exact opposite. Your code never picked up the change that
was made to the gym program in order to support the new format.

What should you do to fix it? What shouldn’t you do?

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