Description:
------------
http://nl.php.net/manual/en/function.uniqid.php

Excerpt, added arrows:
----------------------
string uniqid ( [string prefix [, bool more_entropy]])

uniqid() returns a prefixed unique identifier based on the current time in microseconds. prefix is --> optional <-- but can be useful, for instance, if you generate identifiers simultaneously on several hosts that might happen to generate the identifier at the same microsecond. Up until PHP 4.3.1, prefix could only be a maximum of 114 characters long.

If the --> optional <-- more_entropy parameter is TRUE....
----------------------

So while both parameters should be optional, I do get a warning.

Reproduce code:
---------------
<?php
ini_set('display_errors', '1');
ini_set('track_errors', '1');
error_reporting(E_ALL);

echo uniqid();
?>

Expected result:
----------------
41a6819d003c2

or somesuch.. the same result that I would have gotten with
echo uniqid('');

Actual result:
--------------
Warning: uniqid() expects at least 1 parameter, 0 given in /Library/WebServer/Documents/foo.php on line 7