regex problem

[oracle259]

I have the following regex in my script that is supposed to allow only numbers and letters but for some reason it keeps allowing symbols #$%^*. etc

How can i stop this

[code]
$pattern = "/^(?=.*?[0-9])(?=.*?[a-zA-Z])[a-zA-Z0-9]*$/i";
          $is_pattern = preg_match($pattern, $hash);
          if (!$is_pattern) {
          echo $is_pattern."  Failure";
          } else { echo $is_pattern."  Pass";
       
}
[/code]

[sinisake]

I don't know why your code doesn't work but for same thing i rather use something like this:
[code]
<?php
$text="sg ";
if(eregi("[^a-z 0-9]",$text)){
echo "NO-the string contains illegal characters!";
}
else echo "OK-the string is clean.";

?>
[/code]

[Nicklas]

[code]if (ctype_alnum($hash)) {

echo "String Ok!";

}[/code]