selecting which characters comprise a password

$password = substr(md5(time()),0,6);

[mylungsarempty]

how can i alter

$password = substr(md5(time()),0,6);

to randomly create a password using only the letters a-g?

[stargeek]

$letters = array('a', 'b', 'c'...
array_shuffle($letters);
$password = $letters[0].$letters[1].$letters[2].$letters[3].$letters[4].$letters[5];

this is admitely a little cludgy but it would work.

[mylungsarempty]

the effort is appreciated, but i couldn't get that to work at all.

[stargeek]

there were a few errors in that example, try this instead:

[code]
<?php
$letters = array('a', 'b', 'c', 'd', 'e', 'f', 'g');
srand((float)microtime() * 1000000);
shuffle($letters);
$password = $letters[0].$letters[1].$letters[2].$letters[3].$letters[4].$letters[5]
?>
[\code]

[bcolflesh]

Per the man pages, if you're using PHP >= 4.2.0:
php.net/shuffle

"Note: As of PHP 4.2.0, there is no need to seed the random number generator with srand() or mt_srand() as this is now done automatically."

[stargeek]

I figured that i would incldue the seed line just incase his version is older, i don't think it hurts at all if its a new version.

[mylungsarempty]

Hey, that worked out great -- thankyou

[mylungsarempty]

so if this is my current code:

$letters = array('a', 'b', 'c', 'd', 'e', 'f', 'g');
srand((float)microtime() * 1000000);
shuffle($letters);
$password = $letters[0].$letters[1].$letters[2].$letters[3].$letters[4];

how can i alter this so that each letter does not appear only once? By complete randomness, perhaps 'c' could appear three times, and 'd' could appear twice. What code would allow that to occur?

[bcolflesh]

Put your shuffle in a loop and build the password variable one letter at a time.

[mylungsarempty]

i don't quite understand what that would look like...

[mylungsarempty]

the error i get with the following code is: Fatal error: Cannot break/continue 4 levels in /mnt/web_a/d11/s01/b01b9236/www/asdf.php on line 21

<?php
srand((float)microtime() * 1000000);
$letters = array('a', 'b', 'c', 'd', 'e', 'f', 'g');
while ($password = $letters[0]){
shuffle($letters);
$password = $password . $letters[0];
break 4;
echo $password;
}
?>

what am i doing wrong there?

[dmorison]

Here's a different approach:

$passseed = substr(md5(time()),0,6);

$password = "";

for($i=0;$i<=5;$i++) $password .= chr(97+(ord(substr($passseed,$i,1))%7));

You only want the letters 'a' thru 'g', so this method selects characters out of the ASCII table starting at 97 ('a'); and adding the result of the ASCII value of the i'th character of your seed password "MOD 7", which gives a value between 0 and 6, thus selecting a random character between 'a' and 'g', inclusive.

That was based on your original "how could I alter" question; however you could always just do this:

$password = "";

for($i=0;$i<=5;$i++) $password .= chr(97+rand(0,6));

...which is just as "random".