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How do I use a regular expression to strip C style comments from a file?

by faq_monk (Initiate)
on Oct 08, 1999 at 00:25 UTC ( #665=perlfaq nodetype: print w/replies, xml ) Need Help??

Current Perl documentation can be found at perldoc.perl.org.

Here is our local, out-dated (pre-5.6) version:

While this actually can be done, it's much harder than you'd think. For example, this one-liner

    perl -0777 -pe 's{/\*.*?\*/}{}gs' foo.c

will work in many but not all cases. You see, it's too simple-minded for certain kinds of C programs, in particular, those with what appear to be comments in quoted strings. For that, you'd need something like this, created by Jeffrey Friedl:

    $/ = undef;
    $_ = <>;
    s#/\*[^*]*\*+([^/*][^*]*\*+)*/|("(\\.|[^"\\])*"|'(\\.|[^'\\])*'|\n+|.[^/"'\\]*)#$2#g;
    print;

This could, of course, be more legibly written with the /x modifier, adding whitespace and comments.

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[Eily]: I just wrote a oneliner to solve a (non perl) colleague's problem, and it worked on the first try
[Eily]: and he wasn't impressed
1nickt adds gingersnaps to the platter on the sideboard.
[Eily]: sure it was a pretty standard one liner (of the $h{$1} = $2 if /regex/; END { pp \%h; } variety), but he's not supposed to know that!
[Eily]: what's the point of writing perl if people aren't impressed :P

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