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Asked: 2026-05-15T20:53:03+00:00

I’m using the following regex to strip out non-printing control characters from user input

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I’m using the following regex to strip out non-printing control characters from user input before inserting the values into the database.

 preg_replace('/[\x00-\x1F\x80-\xFF]/', '', $value)

Is there a problem with using this on utf-8 strings? It seems to remove all non-ascii characters entirely.

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1 Answer

  1. Editorial Team

    Part of the problem is that you aren’t treating the target as a UTF-8 string; you need the /u modifier for that. Also, in UTF-8 any non-ASCII character is represented by two or more bytes, all of them in the range \x80..\xFF. Try this:

    preg_replace('/\p{Cc}+/u', '', $value)

    \p{Cc} is the Unicode property for control characters, and the u causes both the regex and the target string to be treated as UTF-8.

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