How to "clear" a string in PHP using regex?

Question

For example, suppose I have

$blah = "C$#@#.a534&";

I want to filter a string so that only letters, numbers and "." remain inferior to "C.a534"

How to do it?

+3

deltanovember May 17 '11 at 10:18

5 answers

answered many times, but:

function cleanit($input){
    return preg_replace('/[^a-zA-Z0-9.]/s', '', $input);
}


$blah = cleanit("C$#@#.a534&");

+4

Lawrence Cherone May 17, '11 at 10:22

$text = preg_replace('/[' . preg_quote('CHARSYOUDONTWANT','/') .  ']/','',$text);

, ,

$text = preg_replace('/[^' . preg_quote('CHARSONLYYOUWANT','/') .  ']/','',$text);

$blah = "C$#@#.a534&";
$blah = preg_replace('/[' . preg_quote('$#@&','/') . ']/','',$blah);
echo $blah;

+2

:

$text = preg_replace('/[^a-zA-Z0-9.]/','',$text);

+1

morja 17 '11 10:23

Replace all invalid characters with an empty string.

0

vichle May 17 '11 at 10:23

jwueller · Accepted Answer · 2011-05-17T10:23:10+0000

If you know what characters should be allowed, you can use a group of negative characters (in a regular expression) to remove everything else:

$blah = preg_replace('/[^a-z0-9\.]/i', '', $blah);

Please note that I use a modifier ifor regular expression. It is case insensitive, so we do not need to specify a-zand a-z.