Question

what does this mean “if ($strength & 2) {” in the following:
I dont understand the $ 2 part…

    function generatePassword($length=11, $strength=7) {
    $vowels = 'aeuy';
    $consonants = 'bdghjmnpqrstvz';
    if ($strength & 1) {
        $consonants .= 'BDGHJLMNPQRSTVWXZ';
    }
    if ($strength & 2) {
        $vowels .= "AEUY";
    }
    if ($strength & 4) {
        $consonants .= '23456789';
    }
    if ($strength & 8) {
        $consonants .= '@#$%';
    }

    $password = '';
    $alt = time() % 2;
    for ($i = 0; $i < $length; $i++) {
        if ($alt == 1) {
            $password .= $consonants[(rand() % strlen($consonants))];
            $alt = 0;
        } else {
            $password .= $vowels[(rand() % strlen($vowels))];
            $alt = 1;
        }
    }
    return $password;
}

Answer 1

& is a bitwise operator. It manipulates the physical bits of a number. & is known as “bitwise AND”. Given two numbers, it will create a new number for all of the shared bits in both numbers.

If you line up the bits for two numbers, any matching bits will be in the resulting number.

 7: 00000111
 2: 00000010

 7 & 2 == 2

This is an easy way to store information in a compact manner.