Question

I currently use this piece of code to reduce a given text to a valid “tagging” format (only lowercase, a-z and minus allowed) by removing/replacing invalid characters

        $zip_filename = strtolower($original);
        $zip_filename = preg_replace("/[^a-zA-Z\-]/g", '-', $zip_filename); //replace invalid chars
        $zip_filename = preg_replace("/-+/g", '-', $zip_filename); // reduce consecutive minus to only one
        $zip_filename = preg_replace("/^-/g", '', $zip_filename); // removing leading minus
        $zip_filename = preg_replace("/-$/g", '', $zip_filename); // remove trailing minus

Any hints on how to put at least the regex into a single one?

Thanks for any advice!

Answer 1

$zip_filename = trim(preg_replace("/[^a-z]+/", '-', $zip_filename),'-');

Explanation:

1. A-Z is useless since it should be lower case
2. Adding + after right bracket will replace one or more consecutive invalid chars
3. Using trim with second parameter – character to trim form beginning and end will speed up the code
4. Removing \- from preg_replace will also take car of hyphens between invalid chars / multiple consecutive hyphens, replacing them to single one.