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I am wondering how much unique results can be accomplished in php by using

rand();

and by using

$num=5;
md5($num.rand());

getrandmax() and you know. May be as low as 32767 on some platforms. Even on Linux 64bit it's only 2^31

If it's unique you need, uniqid() may work

Now how about this one ? how many unique results will the below hash will generate ?

$num=5;
md5($num.rand().uniqid());

Ideally 2^128 since md5 is a 128 bit hash

<?php echo PHP_INT_MAX; ?>

That many.

(2012-09-23, 11:55 AM)sunjava1 Wrote: [ -> ]Now how about this one ? how many unique results will the below hash will generate ?

$num=5;
md5($num.rand().uniqid());

If uniqid() is already unique, what's the point of hashing and adding a 5? It won't be unique anymore since uniqid() is unique and md5() is not.