Q:

PHP - mt_rand function, how to use it to generate a random 20 letter password? 

I've used the manual page on mt_rand(), but I just don't get how the example makes any sense, I guess this is two parts, what defines the min and max, if mt_rand(5,15) can return 1604716014 I suppose its not limited between 5-15.  And how would I regex in some letters to make a password reset generator? 
Thanks

A:

Here's a little bit of script that I like to use to generate a random code:
function generateCode( $charSeed ) { // you can use the username as $charSeed
    $seed = "";
    for ( $i = 1; $i <= 8; $i++ ) {
        $seed .= substr( '0123456789abcdef', rand( 0, 15 ), 1 );
    }
    return md5( $seed .  $charSeed ) .  $seed;
}

You may have misread the documentation.  mt_rand(5,15) or rand(5,15) will absolutely generate a random number between 5 and 15!