- print_r: documentation ( source)
- preg_match_all: documentation ( source)
<?php
$str = '☀+☁️+❄️';
$m = array();
preg_match_all('#(?:(?!e|ln|(?<=l|si|ta)n|pi|(?<=p)i|abs|(?<=a)bs|(?<=ab|co)s|pow|(?<=p)ow|(?<=po)w|a?(?:sin|cos|tan)|(?<=s)in|(?<=c)os|(?<=t)an)[^0-9-+*/()x])+#', $str, $m);
print_r($m);