How Can I Remove Non-Printable Characters from a String in PHP?

Eliminating Non-Printable Characters from String

In some instances, you may encounter the need to remove non-printable characters from a string, such as those within ranges 0-31 and 127 during string manipulation or data cleansing.

7-bit ASCII

To remove non-printable characters in the 7-bit ASCII range (0-31, 127-255), employ the following regular expression using preg_replace:

$string = preg_replace('/[x00-x1Fx7F-xFF]/', '', $string);

This will effectively remove all characters within the specified ranges.

8-bit Extended ASCII

To handle 8-bit extended ASCII, eliminating characters only in range 0-31 and 127, use the adjusted regular expression:

$string = preg_replace('/[x00-x1Fx7F]/', '', $string);

UTF-8

For UTF-8 encoded strings, incorporating the /u modifier in the regular expression is recommended:

$string = preg_replace('/[x00-x1Fx7F]/u', '', $string);

This ensures accurate removal of specific control characters like NO-BREAK SPACE (U 00A0) by adding xA0 to the character class.

Addendum: str_replace Alternative

While preg_replace is efficient, consider str_replace as an alternative, especially for repeated operations.

// Create an array of non-printable characters
$badchars = array(

chr(0), chr(1), chr(2), ..., chr(31),
chr(127)

);

// Replace unwanted characters using str_replace
$str2 = str_replace($badchars, '', $str);

It's important to benchmark the performance of both approaches using your own data to determine the optimal solution for your specific case.

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