Regex: Strip non alpha numeric or punctuation

Question

How can I use PHP to strip out all characters that are NOT alpha, numeric, space, or puncutation?

I\'ve tried the following, but it strip punctuation.

Answer 1

$str = trim($str);
$str = trim($str, "\x00..\x1F");
$str = str_replace(array( ""","'","&","<",">"),' ',$str);
$str = preg_replace('/[^0-9a-zA-Z-]/', ' ', $str);
$str = preg_replace('/\s\s+/', ' ', $str); 
$str = trim($str);
$str = preg_replace('/[ ]/', '-', $str);

Hope this helps.

Answer 2

preg_replace("/[^a-zA-Z0-9\s\p{P}]/", "", $str);

Example:

php > echo preg_replace("/[^a-zA-Z0-9\s\p{P}]/", "", "⟺f✆oo☃. ba⟗r!");
foo. bar!

\p{P} matches all Unicode punctuation characters (see Unicode character properties). If you only want to allow specific punctuation, simply add them to the negated character class. E.g:

preg_replace("/[^a-zA-Z0-9\s.?!]/", "", $str);

Answer 3

You're going to have to list the punctuation explicitly as there is no shorthand for that (eg \s is shorthand for white space characters).

preg_replace('/[^a-zA-Z0-9\s\-=+\|!@#$%^&*()`~\[\]{};:\'",<.>\/?]/', '', $str);