On page 72, the book Effective Perl Programming shows some code to remove C-style comments from a string. I've reproduced the code below.

local $_;

$_ = "
This_Is_Code = 0; /* This is a comment */
/*
 * Can it handle a mult-line comment, i.e.
 * one that goes on for more that one 
 * line? Yes, it can.
*/
This_Is_Code++;
";
                     
for (split m!("(:?\\\W|.)*?"|/\*|\*/)!) {
   if ($in_comment) {
      $in_comment = 0 if $_ eq "*/"
   }  else {
      if ( $_ eq "/*" ) {
         $in_comment = 1;
         print " ";
      } else {
         print;
      }
   }
}

[download]

I have a question about the regular expression that's used in the call to split(). The expression (:?\\\W|.) seems to say match either a non-word character, or any character. Why have both patterns in the alternation when the dot includes non-word characters?

Thanks,

Carl-Joseph

In reply to Alternation in Effective Perl Programming Example by Carl-Joseph

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