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Re: how to comment the lines if found a match

by ww (Archbishop)
on Dec 05, 2008 at 20:55 UTC ( #728378=note: print w/replies, xml ) Need Help??

in reply to how to comment the lines if found a match

Your explanation is adequately clear.

Your answer can be found by using Search (above) or Super Search, as your question is a minor variation on one that comes up again and again.

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Re^2: how to comment the lines if found a match
by kavitha (Initiate) on Dec 05, 2008 at 21:49 UTC
    This is how my program looks like now. I tried this but the grep here is not returning right value, its returning 1 as if its matching all the time.

    #!/usr/bin/perl -w
    open(MATCH_PATTERN,"< temp1");
    open(FILE_TO_LOOK,"< temp2");
    open OF, "> temp3";

    while ($m =<MATCH_PATTERN>)
    print "reading the current text to match \n $m \n";
    seek (FILE_TO_LOOK ,0, 0);
    while ($l= <FILE_TO_LOOK>) {
    print "reading the textline to look for match \n $l \n";
    @found = grep ($m, $l) ;
    $match = @found;
    if ($match == 1)
    print "now the match is \n $match \n";
    print OF "#$l";

    close FILE_TO_LOOK;
    close MATCH_PATTERN;
    close OF;

      You are misunderstanding the use of grep.

      In your example, grep will always return $l unless $m happens to be 0 or an empty string.

      Instead of grep, you probably want a regular expression.

      if($l =~ /\Q$m\E/) { print "We matched\n"; print OF "$$l"; }

      You probably also want to use chomp in the outer loop to remove the line ending from $m.

      You are also writing the file multiple times with different lines commented each time. You might want to generate a list of the expressions to match at the beginning and then loop over the file once.

      G. Wade

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