$re = '`00[A-Fa-f0-9]{2}FF|00FF[A-Fa-f0-9]{2}|FF00[A-Fa-f0-9]{2}|FF[A-Fa-f0-9]{2}00|[A-Fa-f0-9]{2}00FF|[A-Fa-f0-9]{2}FF00`';
$str = '#FF00A0
#00FFC2
#00D3FF
#E400FF
#F5FF00
#FFB100';
preg_match_all($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