Re: REG-EXPR: Allowing limited number of special chars in usernames

Holger Sunke wrote:

I dont know that much aboput regular expressions and just want to know how to find out the number of special (non alphanumeric) characters in a string or how to match a string that contains less than 3 special chars.

I don't really understand what you need, but... - how to find out the number of special (non alphanumeric) characters

  $alpha         = '[a-z0-9]';

$special_chars = preg_replace("/$alpha+/Xi", '', $string); * this would replace any alpha-numeric char by... nothing, leaving

    the "special chars" only, and strlen() will give you how many are

* beware that you're saying *anything* other than alpha-numeric chars - how to match a string that contains less than 3 special chars * as I said above, strlen() will give you the number of these chars: $num_special_chars = strlen($special_chars);

preg_match('/^[ -~äöüßÄÖÜ]+$/',$string)

will return TRUE if $string consists enterily of the chars between the square-brackets. I hope this helped a little.

urrently im using a function function valid_username($string) { if(strlen($string)<=16&&strlen($string)>5) {

      return(preg_match('/^[ -~äöüßÄÖÜ]+$/',$string));

} else {

      return FALSE;

} } This allows usernames of 6 to 16 length containing many special chars and German "Umlaute". But this also allows usernames like "=)/(&%$" what should not be. So how to limit the number of special chars? This function should just return fals if number of special chars > X -- Atentamente, J. Rafael Salazar Magaña Innox - Innovación Inteligente Tel: +52 (33) 3615 5348 ext. 205 / 01 800 2-SOFTWARE http://www.innox.com.mx