mr_dont has asked for the wisdom of the Perl Monks concerning the following question:

O.K. Perl Monks, Lets say I have a file called myfilename.html that looks like this:

<!-- This is an example file -->
<p>this is a link to a book called<br>
<a href="http://www.foobar.tv/booklink.html">
<hr>etc etc

[download]

I wrote a small script that tells me which lines match a certain sting I enter on input, as in:
#>perl filematch.pl book

$matchtext = shift;

$page = "myfilename.html";    
open  PAGE,  $page;
@page_text = <PAGE>;
close PAGE;

    foreach $page_line (@page_text) {
        if ($page_line =~ m/$matchtext/) {
            print "There was an instance of $matchtext\n"; 
            print "on this line:\n";
            print "$page_line\n";
        }
    }

[download]

The code above will tell me there is a match when $matchtext = "book", but it won't match when $matchtext = "booklink". I thought that even though, in my file, "booklink" is surrounded by non-whitespace, it should match nonetheless...

Anybody know what's wrong?

Replies are listed 'Best First'.
(Ovid) Re: Simple REG/EX Question
by Ovid (Cardinal) on Feb 25, 2002 at 22:10 UTC

    I'm not sure what's going on. I tested it and it works for me. I suspect that something changed from when you ran it and when you posted it. Incidentally, here's something a bit closer to how I would write that:

    use strict;

my $matchtext = shift || die &usage;

if ( ! is_valid_pattern( $matchtext ) ) {
    die "'$matchtext' is not a valid regular expression.";
}

my $page = "myfilename.html";
open  PAGE,  "< $page" or die "Cannot open $page for reading: $!";

while (<PAGE>) {
    print "There was an instance of $matchtext on line $.:\n\t$_\n" if
+ /$matchtext/;
}

close PAGE;

sub usage {
    print "Usage: filematch.pl text_to_match";
}

sub is_valid_pattern {
    my $pattern = shift;
    return eval { "" =~ /$pattern/; 1 } || 0;
}

    [download]

    Cheers,
    Ovid

    Join the Perlmonks Setiathome Group or just click on the the link and check out our stats.

[reply]
[d/l]
Re: Simple REG/EX Question
by screamingeagle (Curate) on Feb 25, 2002 at 22:08 UTC
    hi,
    i just ran the code u had posted and this is the output i got :
    There was an instance of book
on this line:
<p>this is a link to a book called<br>

There was an instance of book
on this line:
<a href="http://www.foobar.tv/booklink.html">

    [download]
    so it looks like it is doing what you want it to do...(or am i missing something ?)
[reply]
[d/l]
Re: Simple REG/EX Question
by YuckFoo (Abbot) on Feb 25, 2002 at 22:17 UTC
    No special regex tricks here, 'booklink' should match just as easily as 'book'. But what's gonna happen if you fail to open your file? Maybe you should:

    open(PAGE, $page) || die $!;

    Just in case.

    YuckFoo

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