$ _POST中的字符限制

Question

I have this code and would like to restrict the characters to [a-f][A-F][0-9]

$code = mysql_real_escape_string($_POST['dgt']);
$len = strlen($code);
if (!($len == "32" or $len == "40")) {
   print "This is not a valid code.";
} else {
   echo 'success';
}

right now it has a character LENGTH limit and would like to add characters restriction as stated above.

what's the best possible way to achieve this?

Answer 1

Why don't you make use of a simple regex ?

    if(preg_match('/[^a-f_\-0-9]/i', $code)) //if this regex doesn't work , make use of /[^a-fA-F0-9]/
    {
      if(strlen($code)==32 || strlen($code)==40)
      {
      echo "This is not a valid code.";
      }
    }
    else
    {
    echo 'Success.';
    }