Trying to display a random generated string on my page - php

Question

I'm trying to display a random generated string on my page (php), but I have absolutely no idea how to do this.
I only want the following letters and digits to be used:
B C D F G H J K M P Q R T V W X Y Z 2 3 4 6 7 8 9
In the following format:
XXXXX-XXXXX-XXXXX-XXXXX-XXXXX
Can anyone help me out, and give me a script which I can put on my page? Help would be really appreciated!
I tried this but it's not even displaying on my page for some odd reason.
$tokens = 'BCDFGHJKMPQRTVWXYZ2346789';
$serial = '';
for ($i = 0; $i < 5; $i++) {
for ($j = 0; $j < 5; $j++) {
$serial .= $tokens[rand(0, 35)];
}
if ($i < 3) {
$serial .= '-';
}
}
echo $serial;

Answer 1

You were almost there. Here's a few fixes to your code;
<?php
$tokens = 'BCDFGHJKMPQRTVWXYZ2346789';
$serial = '';
for ($i = 0; $i < 5; $i++) {
for ($j = 0; $j < 5; $j++) {
$serial .= $tokens[rand(0, strlen($tokens) - 1)];
}
if ($i < 4) {
$serial .= '-';
}
}
echo $serial;
?>
I can't say for sure why your page isn't showing, but in your original code you were missing <?php at the top of the page.
Edit: Here's a quick explanation of some of the changes I made to your code.
Your code had rand(0, 35). But since you may change the characters in $tokens in the future, it's better to simply calculate the length of the $tokens using strlen($tokens) - 1 (the -1 being important because strlen() starts counting at 1, whereas $tokens[INDEX] starts counting at 0).
Your code had if ($i < 3), but you actually want four dashes, so I changed it to if ($i < 4).

Answer 2

<?php
$charsPerGroup = 5;
$groups = 5;
$groupDelimiter = '-';
$tokens = explode(' ', 'B C D F G H J K M P Q R T V W X Y Z 2 3 4 6 7 8 9'); // from your question, format this however you want
$tokens = array_flip($tokens);
$resultArray = array();
for($i=0;$i<$groups;$i++) {
$resultArray[] = join(array_rand($tokens, $charsPerGroup));
}
echo join($groupDelimiter, $resultArray);

Answer 3

<?php
$enters = explode(' ', "B C D F G H J K M P Q R T V W X Y Z 2 3 4 6 7 8 9");
$entry = rand(0,count($enters)-1);
echo $enters[$entry];
$output = "";
for($i=1; $i++; $i<=25) {
$entry = rand(0,count($enters)-1);
$output .= $enters[$entry] . ($i % 5 == 0 && $i < 25 ? '-' : '' );
}
echo $output;
?>