Description:
------------
http://php.net/manual/en/pcre.pattern.modifiers.php states that the /u
modifier "... turns on additional functionality of PCRE that is
incompatible with Perl. Pattern strings are treated as UTF-8."

The PCRE documentation itself says "In order process UTF-8 strings, you
must build PCRE to include UTF-8 support in the code, and, in addition,
you must call pcre_compile() with the PCRE_UTF8 option flag. When you do
this, both the pattern and any subject strings that are matched against
it are treated as UTF-8 strings instead of just strings of bytes." This
says, to me, that the /u modifier in our PCRE expressions maps to the
PCRE_UTF8 option flag in the C. 

And, sure enough, preg_match_all('/./u', $string, $matches) puts an
array of all the UTF-8 characters in $string into $matches[0]. 

preg_split('//u', $string) then, by this logic, should return an array
containing the UTF-8 characters in $string. It doesn't--it returns
instead an array of the octets in $string. 

Reproduce code:
---------------
#!/usr/pkg/bin/php
<?php
/* The Euro sign--U+20AC--followed by " hi there", 
   in UTF-8. */
$teststr = "\xe2\x82\xac hi there";

/* Split it into individual characters, passing the /u flag
   to tell PCRE to interpret the string as UTF-8. */
$testchars = preg_split('//u', $teststr, -1, PREG_SPLIT_NO_EMPTY);

/* Get some output that should be equivalent. */
preg_match_all('/./u', $teststr, $matches);
$goodtestchars = $matches[0];

/* The arrays should be the same length. */ 
print "This should be 1: '".(count($testchars) 
        == count($goodtestchars))."'\n";

/* And the octet count of the first entry should be 
   three for both arrays. */
print 'These both should be three: '; 
print strlen($testchars[0]).', '.strlen($goodtestchars[0]).
        "\n";

 ?>

Expected result:
----------------
$ ./testing.php
This should be 1: '1'
These both should be three: 3, 3
$ 

Actual result:
--------------
$ ./testing.php
This should be 1: ''
These both should be three: 1, 3
$ 

This bug has been fixed in CVS.

Snapshots of the sources are packaged every three hours; this change
will be in the next snapshot. You can grab the snapshot at
http://snaps.php.net/.
 
Thank you for the report, and for helping us make PHP better.

The fix will be in PHP 5.0.