Generate Number that is disisble

[kumschick]

how can generate a number that is 9 chr long and divisible by 7?
I have started this but I'm stuk!

ex.: 100000005 / 7 = 14285715

function randompw()
  { 
    global $randpw; 

$pwdenum = range(0, 9);

srand((float)microtime() * 1000000); 
shuffle($pwdenum); 

$randpw = ""; 
for($i = 0; $i < 9; $i++){ 
    $randpw .= $pwdenum[$i]; 
} 
return $randpw; 
  }

randompw();
echo "$randpw";

[MarkR]

EDIT: Totally disregard the algorithm originally posted here, I misread the question.

Mark

[LordShryku]

function randompw() {
   $num = mt_rand(1000000000, 999999999);
   $div = ($num % 7);
   if($div != 0)
      $num -= $div;
   return $num;
}

[kumschick]

no, it has to be a random number. and not 999999994
and no it's not a homework 😉

[LordShryku]

Well then take what you have already and apply the modulus formula. And if it's not to be random, why name it randompw?

[sneakyimp]

ok....it has to be a 9 digit number, right? and divisible by 7?

so it has to be less than or equal to 999999999 and greater than or equal to 100000000

do this: generate a random number between

100000000/7 = 14285714
and
999999999/7 = 142857142

and multiply by 7. like this:

function my_random_number() {
  return 7*rand(14285714, 142857142);
}

if you want to generalize it to make 9-digit numbers divisible by any old number, i leave that exercise up to you! do your homework!

PS: shryku, that's some brutal logic there! damn!

[Installer]

sneakyimp's is the solution I'd use (but raise the floor by one), now that I've seen it, since it would take only one try every time. Here's the one I came up with (on average 7 tries):

function get_9_digit_random()
{
    $i = rand(100000000, 999999999);
    if (($i % 7) != 0) {
        get_9_digit_random();
    } else {
        return $i;
    }
}

BTW, LordShryku's is better than mine, too. He just put one too many 0s in when he posted it. That's why it always came up with the same number.

[sneakyimp]

look at shryku's again...it will work first time almost every time...only flaw is if you get a random number less than 100000005 then it's going to return 99999998 which is 1 digit short. my code has the same problem. the lower bound on mine should be 14285715, not 14285714.

[sneakyimp]

sorry, installer...i just re-said what you did. shryku's script could easily be modified...just raise his floor to 100000005.

[LordShryku]

Lazy Saturday's make you pay less attention to scripting 😃

Didn't think about that lower bound. Good catch 😉