<?php
 
/**
 *
 * @simple function to test password strength
 *
 * @param string $password
 *
 * @return int 
 *
 */
function testPassword($password)
{
    if ( strlen( $password ) == 0 )
    {
        return 1;
    }
 
    $strength = 0;
 
    /*** get the length of the password ***/
    $length = strlen($password);
 
    /*** check if password is not all lower case ***/
    if(strtolower($password) != $password)
    {
        $strength += 1;
    }
 
    /*** check if password is not all upper case ***/
    if(strtoupper($password) == $password)
    {
        $strength += 1;
    }
 
    /*** check string length is 8 -15 chars ***/
    if($length >= 8 && $length <= 15)
    {
        $strength += 1;
    }
 
    /*** check if lenth is 16 - 35 chars ***/
    if($length >= 16 && $length <=35)
    {
        $strength += 2;
    }
 
    /*** check if length greater than 35 chars ***/
    if($length > 35)
    {
        $strength += 3;
    }
 
    /*** get the numbers in the password ***/
    preg_match_all('/[0-9]/', $password, $numbers);
    $strength += count($numbers[0]);
 
    /*** check for special chars ***/
    preg_match_all('/[|!@#$%&*\/=?,;.:\-_+~^\\\]/', $password, $specialchars);
    $strength += sizeof($specialchars[0]);
 
    /*** get the number of unique chars ***/
    $chars = str_split($password);
    $num_unique_chars = sizeof( array_unique($chars) );
    $strength += $num_unique_chars * 2;
 
    /*** strength is a number 1-10; ***/
    $strength = $strength > 99 ? 99 : $strength;
    $strength = floor($strength / 10 + 1);
 
    return $strength;
}
 
/*** example usage ***/
$password = 'php_tutorials_and_examples!123';
echo testPassword($password);
 
?>