January 16, 2004

ISBNs and UPCs

ISBNs and UPCs are directly related. I'm working on a site that helps students to buy and sell used books. ISBN is a key factor. First, it can use ISBNs to automatically pull the author, title, and edition from the Library of Congress database (see earlier post; lots of awesomeness there). But I myself had trouble finding the ISBN of one book because a sticker with the UPC was on top of it. However, the UPC can be used to calculate the ISBN. The first 3 numbers (the country code) for all books are 978. The next 9 are the ISBN (except for the checksum). The last is a UPC checksum. So we can easily extract 9 of the ISBN digits and calculate the final (checksum) digit. my isbn and upc functions (in php)

Posted by Dave at January 16, 2004 12:14 AM | TrackBack