Hi,
I am currently working on a CGI / database search that will be display 5 results per page, and they have to be "random". Actually this just means that each item must have an equal opportunity to appear first in each new search. I have accomplished this easily enough by rearanging the results based on a random number produced each time, then, sending the number to the next page where the db is queried again, so the next page's "random" results are exactly the same as the first, only this time I show the next 5.

my $total_count;   #The total number of items returned by the search
my $newcount = ($total_count - 1);
my $ORDER;    #If this is not the first page, this is the original ran
+dom number keeping the order between pages
if (!$ORDER) { $random_num = int(rand($total_count)) + 1; }
else { $random_num = $ORDER; }
for ($z = 1; $z < $total_count; $z++) {
    my $random = $random_num;
    while ($newcount < $random) {
        $random = ($random - $newcount);
    }
    for ($a = 0; $a <= $count; $a++) {
        if ($a < $random) { push(@front,$nonrandom[$a]); 
        }
        if ($a == $random) { push(@final,$nonrandom[$a]);   
        }
        if ($a < $random) { push(@back,$nonrandom[$a]);  
        }
    }
    @nonrandom = (@back, @front);
    @back = ();
    @front = ();
    $count--;
}

push (@final,$nonrandom[$a]); 

$thispage = $pagenumber * 5;
for ($a = ($thispage - 1); a &lt; ($thispage + 4); $a++) {
    $thispageresults = $final[$a];
}

[download]
Although my solution this time is fine this time, I am sure someone knows a cool way to get truly random results, and pass the same randomness between pages in a CGI script.
I first thought about saving the initial query results, which could be made truely random in a temporary file to be read at each subsiquent call needing that same sequence, but decided that it would be more trouble than it's worth to have to worry about how long the files should be saved, and what would happen if too many visitors did too many differnet searches (with thousands of items returned in the result) filling up my disk space with gigabytes of random replys.

Any ideas and advise would be great!
Kbeen.

In reply to Predictable Randomness by kbeen

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