Question

I admit it’s been a while since I’ve worked with C++, but from what I can tell, my code should work. I’m trying to replace/remove all block comments from a file containing code. I put the whole file I’m searching into a string, and the string contains newline characters.

Here’s my code

std::tr1::regex rx1("[/][*][\S\s]*?[*][/]");
stringName = std::regex_replace(stringName, rx1, std::string(""));

As far as I can tell, this should match /*anything in here including new lines */

I’ve even tested it on http://gskinner.com/RegExr/, where it matches block comments perfectly. Problem is, block comments aren’t being replaced. Is this some kind of TR1 specific bug?

Answer 1

Lightness Races in Orbit pushed me along the right path, but turns out the * and ? cannot be used on arguments within [] brackets. The way to do that is use a noncapturing group which has or statements.

Code to find multi-line block comments:

std::tr1::regex rx3("[/][*](?:\s|.|\n)*?[*][/]");

(?:expression) is how to make a noncapturing group. You can apply the * and ? to the outside of that. Inside of it, use | as an or statement.