random value

phpprog

Hi all
I want to generate a random number between say (min, max)
But i dont want the same number more than once.
Is it possible??

Thanks
IM

stolzyboy

have you checked out the rand() function at php, not sure how to stop dupes though, since it is random, you can have a random number twice, you would probably have to track it in a database somehow

jmarco

I use mt_rand($min, $max); supposedly it generates a better random value.

Sxooter

Originally posted by phpprog
Hi all
I want to generate a random number between say (min, max)
But i dont want the same number more than once.
Is it possible??

Thanks
IM

What you are describing is shuffling, just like a deck of cards. What you do is similar.

Assuming you need to keep the data, you can make an array like this:

# include srand functions here
$arr = range(0,99);
shuffle($arr);
print array_pop($shuffle);

Then you can serialize it and store it somewhere and get it back, and do another array_pop (with or without a shuffle if you want one.) and store it again, or you could store it in a database or somewhere else.

Sxooter

Note that another cool trick for this is to create a table in a database that has a two columns one for used and one for the value, like so:

nums:

num | used

0 | t
1 | f
2 | f
3 | f
4 | f
5 | f
6 | t
7 | t
8 | f
9 | t

and so on.

then you can detect if you need to shuffle because there aren't enough values left:

select count(*) from nums where used is true;

if that count is < a certain threshold, then you can "reshuffle" by just

update nums set used = FALSE;

then to get a random row, you just use

select num from nums where used is false order by random();

Then, you use

update nums set used = true where num='num';

to mark the row used.