The ISBN-10 verification process is used to validate book identification
numbers. These normally contain dashes and look like:
The ISBN-10 format is 9 digits (0 to 9) plus one check character (either a digit or an X only). In the case the check character is an X, this represents the value ‘10’. These may be communicated with or without hyphens, and can be checked for their validity by the following formula:
(x1 * 10 + x2 * 9 + x3 * 8 + x4 * 7 + x5 * 6 + x6 * 5 + x7 * 4 + x8 * 3 + x9 * 2 + x10 * 1) mod 11 == 0
If the result is 0, then it is a valid ISBN-10, otherwise it is invalid.
Let’s take the ISBN-10
3-598-21508-8. We plug it in to the formula, and get:
(3 * 10 + 5 * 9 + 9 * 8 + 8 * 7 + 2 * 6 + 1 * 5 + 5 * 4 + 0 * 3 + 8 * 2 + 8 * 1) mod 11 == 0
Since the result is 0, this proves that our ISBN is valid.
Given a string the program should check if the provided string is a valid ISBN-10. Putting this into place requires some thinking about preprocessing/parsing of the string prior to calculating the check digit for the ISBN.
The program should be able to verify ISBN-10 both with and without separating dashes.
To ensure the correctness of your implementation, see test.sh with usage:
sh test.sh /path/to/program
It is expected that your program takes as its only argument the ISBN, and exits successfully when it is valid and with exit code 1 when it is not.
All submissions must contain a statement that the code is your own work (groups are ok!) and placing the code under either CC0, CC-BY, or CC-BY-SA. Submissions are by email to email@example.com. Attaching each source file is preferred, but tarballs or git URLs will also be accepted (especially when directory structure matters). Submissions may be in any programming language that can be compiled or interpreted on a Debian Stable system.
If relevant, please make it clear what name, pseudonym, or group name you would like your submission attributed to. This name (and the code content of your submission) will be made public.
Submissions are due by and the winning teardown post will be published the following month.
This exercise and its tests based on https://github.com/exercism/rust/tree/master/exercises/isbn-verifier, original license:
Copyright (c) 2017 Exercism, Inc
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
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