Random Number Every Week

[cookiemonster]

Hi,

Is there any way I can make a PHP code that echoes a different random number once a week?

Thanks in advance.

[eelixduppy]

Create a seed that only changes once per week (e.g. by using the week number 1-52) and then feed it to srand(). This will give you the same set of random numbers for the whole week, but will change at the beginning of a new week.

[cookiemonster]

Thank you eelixduppy, that sounds promising.

Do you think you could supply a sample code? I am fairly new to PHP and have only a vague idea of what you are suggesting.

Thanks again!

[Readie]

I think this'll work... I'm not waiting around for a week to test it though :P

srand(floor(date('U')) / (60*60*24*7));
echo rand() % 100;

Doesn't quite follow eelix's idea, as I think that basing it by week number will actually loop year-on-year.

This is based on seconds since the unix epoch, so it should hopefully not be predictable at all without actually knowing the code.

[cookiemonster]

Readie,

Thanks for the response ... what exactly is the '% 100' used for in this script?
I'll check the script again in one week to see if it works ... unless there is some way to modify it to work every hour for testing purposes?

Thanks again.

[cookiemonster]

Oh, I realize now that % 100 is, for example, the random number between 0 and 100 (%500 would be between 0 and 500).
Can the 100 somehow be substituted for a variable? For example,

echo rand() % $stuff

?

[Readie]

% 100 returns the remainder after having divided by 100.

You could replace it with a variable however, yes.

[cookiemonster]

Readie, your solution was working wonderfully up until now.
After two days, the number changed!

Here is my EXACT code -

<?php
srand(floor(date('U')) / (60*60*24*7)); 
$num = 100;
$a = rand() % $num;
echo $a;
echo "<br>";
$b = rand() % $num;
echo $b;
echo "<br>";
$c = rand() % $num;
echo $c;
echo "<br>";
$d = rand() % $num;
echo $d;
echo "<br>";
$e = rand() % $num;
echo $e;
?>

[Readie]

Well you wanted a randum number every week, see if the number changes again in another seven days before thinking it's broken :)

If you want to set an off-set for this by the way (say, you want it to change on a Monday rather than a Thursday, or at a different hour, minute or even second) then this code should allow you to fine-tune it a bit:

$day_offset = 0;
$hour_offset = 0;
$minute_offset = 0;
$second_offset = 0;

srand(floor(date('U') / ((60*60*24*7) + (((60*60*24) * $day_offset) + ((60*60) * $hour_offset) + (60 * $minute_offset) + $second_offset));
echo rand() % 100;

Change those offset variables to +/- when the number changes.

[Readie]

Man what was I thinking when I typed that...

$day_offset = 0;
$hour_offset = 0;
$minute_offset = 0;
$second_offset = 0;

srand(floor((date('U') + (60 * 60 * 24 * $day_offset) + (60 * 60 * $hour_offset) + (60 * $minute_offset) + $second_offset) / (60 * 60 * 24 * 7));
echo rand() % 100;

Is what you really want.

[cookiemonster]

Yeppers ... you were right Readie - apparently it changes on Thursdays.
Works PERFECTLY now!

Thanks again!