how to remove c++ comments from a cpp file?

[Frank Potter]

On Jan 26, 5:08 pm, Gary Herron <gher... at islandtraining.com> wrote:
> Frank Potter wrote:
> > I only want to remove the comments which begin with "//".
> > I did like this, but it doesn't work.
>
> > r=re.compile(ur"//[^\r\n]+$", re.UNICODE|re.VERBOSE)
> > f=file.open("mycpp.cpp","r")
> > f=unicode(f,"utf8")
> > r.sub(ur"",f)
>
> > Will somebody show me the right way?
> > Thanks~~If you expect help with a problem, it would be nice if you told us what
> the problem is. What error did you get?
>
> But even without that I see lots of errors:
>
> You must import re before you use it:
> import re
>
> Open a file with open((..) not file.open(...).
>
> Once you open the file you must *read* the contents and operate on that:
> data = f.read()
>
> Then you ought to close the file:
> f.close()
>
> Now you can do your sub on the string in data -- but note, THIS WON'T
> CHANGE data, but rather returns a new string which you must assign to
> something:
>
> new_data = r.sub(ur"", data)
>
> Then do something with the new string.
>
> Also I fear your regular expression is incorrect.
>
> Cheers,
> Gary Herron

Thank you.
I'm very sorry because I was in a hurry when I post this thread.
I'll post again my code here:
[CODE]
import re

f=open("show_btchina.user.js","r").read()
f=unicode(f,"utf8")

r=re.compile(ur"//[^\r\n]+$", re.UNICODE|re.VERBOSE)
f_new=r.sub(ur"",f)

open("modified.js","w").write(f_new.encode("utf8"))
[/CODE]

And, the problem is, it seems that only the last comment is removed.
How can I remove all of the comments, please?