I'd like to make sort of a comment remover for C++.

If there's a source file like bellow...

<source.txt>
// 1234
12//34
///1234
12///34

and my code is...

file = open("source.txt", "r")
file.each_line {|line|
   if line.match /(.*)\/\//
      puts $1 if $1.length > 0
   end
}
file.close

result is...

12
  /
12/

but!, what I expected is~

12
12

What's wrong with this code...(I think I may not understand regular
expression totally...) and what should I do for this?