FYI - if you are trying to scan from a string which contains a filename with extension. For instance:
<?php
$out = sscanf('file_name.gif', 'file_%s.%s', $fpart1, $fpart2);
?>
The scanned string in the $fpart1 parameter turns out to be 'name.gif' and $fpart2 will be NULL.
To get around this you can simply replace the "." with a space or another "white-space like" string sequence.
I didn't see any other comments on regarding string literals which contain a '.' so I thought I'd mention it. The subtle characteristics of having "white-space delimited" content I think can be a source of usage contention. Obviously, another way to go is regular expressions in this instance, but for newer users this may be helpful.
Just in case someone else spent 10 minutes of frustration like I did. This was seen on PHP Version 5.2.3-1ubuntu6.3.
Searching the bug reports shows another users misunderstanding: http://bugs.php.net/bug.php?id=7793