I'm having trouble creating a random string

Question

I have a little script that is used to generate a random string of 25 characters. It works about 70% of the time and other times it creates strings that are only 10.

$unique = substr(md5(microtime()),rand(0,26),25);

My goal is to have a random string of (lower case) letters and numbers without having to create a function

Answer 1

This is becouse you are cutting it to a random length with rand(0, 26).

Try this instead:

$unique = substr(md5(microtime()), 0, 25);

Answer 2

Don't use md5(microtime()). You might think it's more secure than md5(rand()), but it isn't.

With a decent amount of tries and a method of syncing (like a clock on your website) one can predict the result of microtime() to the millisecond.

use md5(rand())

or if you want it to be more secure use md5(microtime().rand())