string sanitizer for filename

Question

I\'m looking for a php function that will sanitize a string and make it ready to use for a filename. Anyone know of a handy one?

( I could write one, but I\'m worri

Answer 1

SOLUTION 1 - simple and effective

$file_name = preg_replace( '/[^a-z0-9]+/', '-', strtolower( $url ) );

• strtolower() guarantees the filename is lowercase (since case does not matter inside the URL, but in the NTFS filename)
• [^a-z0-9]+ will ensure, the filename only keeps letters and numbers
• Substitute invalid characters with '-' keeps the filename readable

Example:

URL:  http://stackoverflow.com/questions/2021624/string-sanitizer-for-filename
File: http-stackoverflow-com-questions-2021624-string-sanitizer-for-filename

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SOLUTION 2 - for very long URLs

You want to cache the URL contents and just need to have unique filenames. I would use this function:

$file_name = md5( strtolower( $url ) )

this will create a filename with fixed length. The MD5 hash is in most cases unique enough for this kind of usage.

Example:

URL:  https://www.amazon.com/Interstellar-Matthew-McConaughey/dp/B00TU9UFTS/ref=s9_nwrsa_gw_g318_i10_r?_encoding=UTF8&fpl=fresh&pf_rd_m=ATVPDKIKX0DER&pf_rd_s=desktop-1&pf_rd_r=BS5M1H560SMAR2JDKYX3&pf_rd_r=BS5M1H560SMAR2JDKYX3&pf_rd_t=36701&pf_rd_p=6822bacc-d4f0-466d-83a8-2c5e1d703f8e&pf_rd_p=6822bacc-d4f0-466d-83a8-2c5e1d703f8e&pf_rd_i=desktop
File: 51301f3edb513f6543779c3a5433b01c