Regex to strip comments and multi-line comments and empty lines

$text = preg_replace('!/\*.*?\*/!s', '', $text);
$text = preg_replace('/\n\s*\n/', "\n", $text);

Keep in mind that any regex you use will fail if the file you're parsing has a string containing something that matches these conditions. For example, it would turn this:

print "/* a comment */";

Into this:

print "";

Which is probably not what you want. But maybe it is, I don't know. Anyway, regexes technically can't parse data in a manner to avoid that problem. I say technically because modern PCRE regexes have tacked on a number of hacks to make them both capable of doing this and, more importantly, no longer regular expressions, but whatever. If you want to avoid stripping these things inside quotes or in other situations, there is no substitute for a full-blown parser (albeit it can still be pretty simple).

//  Removes multi-line comments and does not create
//  a blank line, also treats white spaces/tabs 
$text = preg_replace('!^[ \t]*/\*.*?\*/[ \t]*[\r\n]!s', '', $text);

//  Removes single line '//' comments, treats blank characters
$text = preg_replace('![ \t]*//.*[ \t]*[\r\n]!', '', $text);

//  Strip blank lines
$text = preg_replace("/(^[\r\n]*|[\r\n]+)[\s\t]*[\r\n]+/", "\n", $text);

$string = preg_replace('#/\*[^*]*\*+([^/][^*]*\*+)*/#', '', $string);