Remove all non-alphanumeric characters using preg_replace

Question

How to remove all non-alphanumeric characters from a string in PHP?

This is the code I'm currently using:

$url = preg_replace('/\s+/', '', $string); 

It replaces only spaces.

Answer 1

 $url = preg_replace('/[^\da-z]/i', '', $string); 

Answer 2

Take it first, how would I do it

 $str = 'qwerty!@#$@#$^@#$Hello%#$'; $outcome = preg_replace("/[^a-zA-Z0-9]/", "", $str); var_dump($outcome); //string(11) "qwertyHello" 

Hope this helps!

Answer 3

Not sure why no one else suggested this, but this seems to be the simplest regular expression:

 preg_replace("/\W|_/", "", $string) 

You can also see this in action: http://phpfiddle.org/lite/code/0sg-314

Answer 4

 preg_replace('/[\s\W]+/', '', $string) 

It seems to work, in fact the example was in the PHP documentation on preg_replace

Answer 5

 $alpha = '0-9a-z'; // what to KEEP $regex = sprintf('~[^%s]++~i', preg_quote($alpha, '~')); // case insensitive $string = preg_replace($regex, '', $string); 

Answer 6

you can use

 $url = preg_replace('/[^\da-z]/i', '', $string); 

You can use Unicode characters,

 $url = preg_replace("/[^[:alnum:][:space:]]/u", '', $string);