It is REALLY essential to make sure that srand is called only once.
This is a bit difficult if the call is hidden somewhere in third-party code you include. For example, I used a standard banner script that *seemed* to work well putting
three random banners in one frame. But in the long run, the choice appeared
somewhat biased - probably because srand was called once per banner, not
once per run.
It would be nice if the random number generator worked like in PERL: If You use the random function without having called srand ever before in a script,
srand is invoked before (and automatically with a nice seed, hopefully).
I suggest that one should do something like this:
<?php
if (!$GLOBALS["IHaveCalledSrandBefore"]++) {
srand((double) microtime() * 1000000);
}
?>
(Depending on the situation, one might also work with a static variable instead)
