$re = '/(^[0-9]{1,2}/[0-9]{1,2}/[0-9]{1,2}), ([0-9]{1,2}:[0-9]{1,2} [a-zA-Z]{2}) - ([a-z0-9 \S]+?)(:| added|created group) ([a-z0-9 \S\n]+)?/';
$str = '3/22/16, 12:35 PM - Narayanaswamy Meetup Hsp: Guys Ranjit is proposing to have a Holi walk (not Holy walk) on Thursday 24-3-16. He will put up the proposal and if anyone wishes to join pl co-ordinate with Ranjit';
preg_match($re, $str, $matches, PREG_OFFSET_CAPTURE, 0);
// Print the entire match result
var_dump($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