Question

I’m writing my own minifying tool for practice (regular expresssions practice), but after a few tutorials I’m still not getting it.

For example I’m trying to find and remove all comments from my CSS file and that includes:

1. Single line comments as in

   /** single line comment ****/ or

   /****single line comment */ and

2. Multi line comments as in

   /**** start of comment

   .myCssClass

   {

   font:13pt Arial;
   

   }

********* end of comment **/

So far I’m using an expression which can only deal with single line comments as follows

(\/\*.*\*\/)

But what I’m trying to understand about regular expressions is how do I tell the regex engine to span lines as well. I did try this:

(\/\*[.\n]*\*\/)

which doesn’t work at all.

Anyone know where I’m going wrong?

Thanks,
Jacques

Answer 1

If you’re running the match in C#, have you tried RegexOptions?

Match m = Regex.Match(word, pattern, RegexOptions.Multiline);

“Multiline mode. Changes the meaning of ^ and $ so they match at the beginning and end, respectively, of any line, and not just the beginning and end of the entire string.”

Also see Strip out C Style Multi-line Comments

EDIT:

OK..looks like an issue w/ the regex. Here is a working example using the regex pattern from http://ostermiller.org/findcomment.html. This guy does a good job deriving the regex, and demonstrating the pitfalls and deficiencies of various approaches. Note: RegexOptions.Multiline/RegexOptions.Singleline does not appear to affect the result.

string input = @"this is some stuff right here
    /* blah blah blah 
    blah blah blah 
    blah blah blah */ and this is more stuff /* blah */
    right here.";

string pattern = @"(/\*([^*]|[\r\n]|(\*+([^*/]|[\r\n])))*\*+/)";
string output = Regex.Replace(input, pattern, string.Empty, RegexOptions.Singleline);