password validation

[laura_60]

Hello

I was wondering if there was an easy way to validate a password to make sure it is over a certain length and that it is alphanumeric. I know i can check the string length with the strlen function but I am not sure how to check if it is alphanumberic.

Thanks

[John_Canyon]

function isAlphaNumeric($string)
{
	for($i=0;$i<strlen($string);$i++)
	{
		if(!preg_match("/^[a-z0-9 ]/i",substr($string,$i,1)))
		{
			return false;
		}
	}
	return true;
}

There might be an easier way to do this.. but whipped it
up this way real quick for ya.

Cheers

[br__ken]

this regex would work too:

<?
$pw="asdf01";

function isValid($pw){
	return preg_match("/^[a-z0-9]{3,}$/i",$pw);
}

echo (isValid($pw))?"Valid":"Not Valid";
?>

oh, to allow spaces in the pw just put a " "(space) after the 0-9
and to make the password 3-x chars long, change the {3,} to {3,max}

[laserlight]

actually, instead of regex, in your case there is the simple ctype_alnum() function.

//set locale to only accept a-zA-Z for alpha
setlocale(LC_CTYPE, 'C');
if (strlen($password) > 3 && ctype_alnum($password))
	//ok
else
	//unacceptable

[laura_60]

Thanks for the replies. This is how i did it.

	  // check if password has letters and numbers
	  $data = array($password);
	  $file = preg_grep("/[[:digit:]]/", $data); 
	  $file2 = preg_grep("/[[:alpha:]]/", $data);
	  if ($file[0]=="" || $file2[0]=="")
	  {
	  	$bad=1;
		echo("<center><p class='Headings'>Password has to contain letters and numbers</center></p>");
	  }