<?php
$comment = '
<!--This is a comment. <!--This is a comment. Comments are not displayed in the browser --><!--This is a comment. Comments are not displayed in the browser--> Comments are not displayed in the browser-->';
preg_match_all('/(\<!--\s*.*?((--\>)|$))/imsx', $comment, $matches);
var_dump($matches);
array(4) {
[0]=>
array(2) {
[0]=>
string(91) "<!--This is a comment. <!--This is a comment. Comments are not displayed in the browser -->"
[1]=>
string(67) "<!--This is a comment. Comments are not displayed in the browser-->"
}
[1]=>
array(2) {
[0]=>
string(91) "<!--This is a comment. <!--This is a comment. Comments are not displayed in the browser -->"
[1]=>
string(67) "<!--This is a comment. Comments are not displayed in the browser-->"
}
[2]=>
array(2) {
[0]=>
string(3) "-->"
[1]=>
string(3) "-->"
}
[3]=>
array(2) {
[0]=>
string(3) "-->"
[1]=>
string(3) "-->"
}
}