PHP random set of images - php

Question

I'm using a php script to randomly show images. I've duplicated this script three times because I wanted to show three random images at once - I'm unsure of how to change the php code to show 3 images.
The problem is, I don't want to run into the chance of all three scripts showing the same images at once. Is there something that I could add to this code to make sure that each image displayed is always different?
<?php
$random = "random.txt";
$fp = file($random);
srand((double)microtime()*1000000);
$rl = $fp[array_rand($fp)];
echo $rl;
?>
the html:
<?php include("rotate.php"); ?>
<?php include("rotate.php"); ?>
<?php include("rotate.php"); ?>
*the random.txt just has a list of filenames with links.

Answer 1

Simple solution...
Get the array of random images (you already did this)
Shuffle the array
Pop an image off the end of the array whenever you need one
rotate.php
$random = "random.txt";
$fp = file($random);
shuffle($fb); //randomize the images
in your code
<?php include('rotate.php') ?>
Whenever you need an image
<?php echo array_pop( $fb ) ?>
http://php.net/manual/en/function.array-pop.php

Answer 2

function GetRandomItems($arr, $count)
{
$result = array();
$rcount = 0;
$arrsize = sizeof($arr);
for ($i = 0; ($i < $count) && ($i < $arrsize); $i++) {
$idx = mt_rand($rcount, $arrsize);
$result[$rcount] = trim($arr[$idx]);
$arr[$idx] = $arr[$rcount];
$rcount++;
}
return $result;
}
$listname = "random.txt";
$list = file($listname);
$random = GetRandomItems($list, 3);
echo implode("<BR>", $list);
P.S. Actually, Galen's answer is better. For some reason I forgot about shuffle xD

Answer 3

You can use array_rand() to select more than one random key at a time, like this:
$random = "random.txt";
$fp = file($random);
shuffle($fp);
// You don't need this. The array_rand() function
// is automatically seeded as of 4.2.0
// srand((double)microtime()*1000000);
$keys = array_rand($fp, 3);
for ($i = 0; $i < 3; $i++):
$rl = $fp[$keys[$i]];
echo $rl;
endfor;
This would eliminate the need for including the file multiple times. It can all be done at once.

Answer 4

You could write a recursive function to check if the array ID has already been printed, and if it has, call itself again. Just put that in a for loop to print three times :)
Though keep in mind that truly random images could overlap!
$beenDisplayed = array();
function dispRand($id) {
if (in_array($id, $beenDisplayed)) {
//generate random number
dispRand($id);
}
else {
array_push($beenDisplayed, $id);
}
}
for ($i = 0; $i < 3; $i++) {
dispRand($random_id);
}