I recent asked about the random image generator thing, and I got it to work by using a random number generator.

Here is my current code:

<?php
// here is the dir of images, images are named "filename_###-thumb.jpg"
//where ### is a sequence number of 001 - 999
$dir = "thumbs/";

// here, it counts how many files are in the dir
$total_files = count(glob($dir . "*.jpg"));

// here is the number generator in three digits
$int = str_pad(mt_rand(1, $total_files), 3, 0, STR_PAD_LEFT);

// and here is the echo of the random image where $int is the random 3 digit number
echo '<a href="/games/sf4/screenshots/char_trailer/full/char_'.$int.'.jpg"><img src="/games/sf4/screenshots/char_trailer/thumbs/char_'.$int.'-thumb.jpg"></a>';

?>

problem i am having with this is, it will generate duplicate numbers. meaning that if i want to display 6 random images in a 3x2 table, it will have a duplicate here or there. although the range of numbers is wide, but duplicates will still happen.

is there a way for me to randomize those number without duplicates? i've checked all over the web but they only supply non-duplicate number in a small range like 1 - 10.

You will need to save each generated numbers into an array, and regenerate again and again until you have no clash.

This code is in python, but just to give you an idea:

import random

shooters={}
while len(shooters)<4:
  id=random.randint(0,9999999)
  while id in shooters.keys():
    id=random.randint(0,9999999)
  #end while
  shooters[id]=True
#end while
print shooters

I use something like this to check availability of threads in a daemon.
When the thread is active, there is an shooters[id] value. When activity stops, the threads update shooters to remove it's id.
I needed random values without clash for this to work without conflicts.