$re = '/[[:blank:]]/u';
$str = 'ALL_CHARS:
SPACES :
tab{ }
space{ }
nobreakspace{ }
narrownobreakspace{ }
enquad{ }
emquad{ }
enspace{ }
emspace{ }
threeperemspace{ }
fourperemspace{ }
sixperemspace{ }
figurespace{ }
punctuationspace{ }
breakablethinspace{ }
hairspace{ }
ZERO-WIDTH SPACES :
zerowidthspace{}
zerowidthnobreakspace{}
JOINERS :
wordjoiner{}
zerowidthnonjoiner{}
zerowidthjoiner{}
';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php