$re = '/([<>]=?)|=/';
$str = '4>3
3<5
4<=4
5>=5
4=4
5>>3
3<<5
5==5
10>5=>5>2.5=<20>10
';
preg_match_all($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