nithinbekal / isbn Goto Github PK

ISBN.convert_10_to_13("0-448-06004-3")

Result: 97804480600410
Expected: 9780448060040

I ran across this ISBN the other day: 140003471x

Amazon Link: https://smile.amazon.com/Chronicle-Foretold-Gabriel-Garc%C3%ADa-M%C3%A1rquez/dp/140003471X/ref=smi_www_rco2_go_smi_g1405964225?_encoding=UTF8&%2AVersion%2A=1&%2Aentries%2A=0&ie=UTF8

Sometimes an “X” appears—and what it actually means is “10.” Here’s why:
The ISBN has several parts which are all code for something. The final digit is known as the “check digit” and it verifies the ISBN. Check digits go from 0 to 10. In cases where the check digit would be 10, it appears as an X. The X only appears in 10-digit ISBNs. Source: https://rachellegardner.com/isbn-10-isbn-13-and-those-pesky-x%E2%80%99s/

So, I think when the check-digit is 10 for a 10-digit ISBN, it should check for the presence of an "x" rather than a "10" (which does not fit into a single digit).

Ran across this valid ISBN: 9781531019730, which is valid but ISBN.valid?(9781531019730) returns false.