Re: what's wrong with this while loop?

the problem with your loop is that after php enters it, it can't get out because there is no break, nor a way to turn the expression to false. Normally, you have a loop which always evaluates to TRUE, and when it doesn't, you want to quit. And even when this is not how you did it, eg with while(true){ ... }, then you can bail out using break. However, you did none of those here. Your loop starts with while($tot < $sum) { [...] } and doesn't in any way modify the value of any of both inside the (double!) loop, nor does it ever break. So, you're stuck with an eternal loop as a result. Besdies that, I'm wondering what you need the while()-loop for anyway, since it's utterly useless in your code. An easier way would be to code it like this: $rand_pass = ''; for ($i = 0; $i < $length; $i++){ $rand_pos = rand(0, $rand_max); $rand_key .= $key_chars{$rand_pos}; } $somecontent = "new key: $rand_pass\n"; echo $somecontent; bo wrote:

Following my code is to write a 15digit random generated password into a file named test.txt. I was trying to keep it random generating 100 passwords and be written into test.txt by using a while loop, however, the result is strange. Take a look at the code (most of it is from php.net) and what's wrong with this while loop? besides, if I generate a large sum of passwords,say 50 million, will it be repetitive? Thank you! <?php /* <meta HTTP-EQUIV="REFRESH" content="1; url=http://svr/rand.php"> */

$length    = 15;
$sum       = 100;
$key_chars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789';

$rand_max = strlen($key_chars) - 1; $filename = 'test.txt'; $tot=0; while($tot < $sum){ for ($i = 0; $i < $length; $i++){ $rand_pos = rand(0, $rand_max); $rand_key[] = $key_chars{$rand_pos}; } $rand_pass = implode('', $rand_key); $somecontent = "$tot $rand_pass\n"; echo $somecontent; $filename = 'test.txt'; // Let's make sure the file exists and is writable first. if (is_writable($filename)) { // In our example we're opening $filename in append mode. // The file pointer is at the bottom of the file hence // that's where $somecontent will go when we fwrite() it. if (!$handle = fopen($filename, 'a')) {

         echo "Cannot open file ($filename)";
         exit;

} // Write $somecontent to our opened file. if (fwrite($handle, $somecontent) === FALSE) {

       echo "Cannot write to file ($filename)";
       exit;

} echo "Success, wrote ($somecontent) to file ($filename)"; fclose($handle); } else { echo "The file $filename is not writable"; } $tot++; } ?>