in reply to Perl & Regex

If you would like to use a regex as a variable, you should use qr. For example: 
use strict;

my $string = 'Price: $21343.355344';
my $searchString = qr|^Price: \$([0-9]+\.[0-9]+)|;

if($string =~ /$searchString/)
{
  print "Matches: $1\n";
}
else
{
  print "No Match: $`\n";
}

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I think you are getting messed up because $( gets replaced with $REAL_GROUP_ID (ie $( ...)

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Re^2: Perl & Regex
by Kzin (Acolyte) on Sep 08, 2004 at 23:33 UTC
    Thanks I will try qr =) Will post again if I have a problem still. Sounds like this could solve the problem I am having.
[reply]
Re^2: Perl & Regex
by Anonymous Monk on Sep 09, 2004 at 09:57 UTC
    > If you would like to use a regex as a variable, you should use qr.

    Not always. There are some advantages to using qr. There are some disadvantages as well. 1) qr takes more memory than a string, which may matter if you have a lot of them. 2) in some cases, if you construct a large regex out of many small parts, qr is significantly slower than using strings - this is because in non-trivial interpolations, a qr-ed regex first gets stringified, which gives lots of extra parenthesis. 

    #!perl -w
use Devel::Size 'size';

print size('Price: \$([0-9]+\.[0-9]+)'), "\n";
print size(qr/Price: \$([0-9]+\.[0-9]+)/), "\n";
__END__
50
104

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[d/l]
[select]
Re^2: Perl & Regex
by Kzin (Acolyte) on Sep 08, 2004 at 23:32 UTC
    edited out
[reply]
Re^2: Perl & Regex
by Kzin (Acolyte) on Sep 09, 2004 at 00:11 UTC
    Allright, that didn't quite seem to do the trick...
    Ok here is the code, however I have changed the company to one *similar* to my own, just for example purposes. I dont claim affiliation to these guys disclaimer stuff goes here. 
    #!/usr/bin/perl

        use LWP::UserAgent;
        use Net::SMTP;
        $ua = LWP::UserAgent->new;

        my ($req, $match, $res, $name, $url, $price, $readPath, $write
+Path, $companyName, $ccemail);
        my $changes="";
        my $searchString="";
        my $searchString2="";

        $email = 'wmkzin@hotmail.com';

# $tag represents a <blah> tag in html
        $tag = "<[^>]*>";

        $readPath = "/home/autotasks/pricemonitor/";
        $companyName = "LensMart";
        $searchString = qr|^Price: \$([0-9]+\.[0-9]+)|;
        $searchString2 = qr|^Price: $tag\$([0-9]+\.[0-9]+)|;

        open( CONTACTS, "<$readPath$companyName" ) ; # list being read
        open( CONTACTS2, ">$readPath.$companyName"); # new list being 
+generated

        while( <CONTACTS> )
        {
                chomp($_);
                ($name, $url, $price) = split(/###/, $_);
                $savename = $name;
                $name =~ s/\(/\\(/g;
                $name =~ s/\)/\\)/g;
                $req = HTTP::Request->new(GET => $url);
                $res = $ua->request($req);
                $_ = $res->content;
 
                # the "if" statement below looks for the product name 
+and price
                if( /$searchString/ )
                {
                        $match = $1;
                        # check if price is the same
                        if( $1 == $price ) {}
                        else
                        {
                                # price changed, so add to "changes" l
+ist
                                $changes .= "$savename($url) - changed
+ from \$$price to \$$1 \n\n";
                        }
                        print CONTACTS2 "$savename###$url###$1\n";
                } elsif ( $searchString2 ne "" )
                {
                        if( /$searchString2/ )
                        {
                                $match = $1;
                                # check if price is the same
                                if( $1 ne $price )
                                {
                                        # price changed, so add to "ch
+anges" list
                                        $changes .= "$savename($url) -
+ changed from \$$price to \$$1 \n\n";
                                }
                                print CONTACTS2 "$savename###$url###$1
+\n";
                        }else
                        {
                                print CONTACTS2 "$savename###$url###$p
+rice\n";
                                $changes .= "No match on $savename($ur
+l)\n\n";
                        }
                }else
                {
                        print CONTACTS2 "$savename###$url###$price\n";
                        $changes .= "No match on $savename($url)\n\n";
                }
        }

        close( CONTACTS );
        close( CONTACTS2);

        # copy new list onto old one to ensure things are the same nex
+t time
        system( "cp $readPath.$companyName $readPath$companyName" );

        # if prices changed, email
        if( $changes ne "" )
        {
                system ("date");
                print "$companyName:\n$changes";
                $smtp = Net::SMTP->new('localhost'); # connect to an S
+MTP server
                $smtp->mail( $email );

                if ($ccemail ne "")
                {
                        $smtp->to($email, $ccemail);
                }else
                {
                        $smtp->to($email);
                }
                $smtp->data();

                # Send the header.
                $smtp->datasend("To: $email \n");
                $smtp->datasend("From: $email\n");
                $smtp->datasend("Subject: $companyName Price Changes\n
+");
                $smtp->datasend("\n");

                # Send the body.
                #
                $smtp->datasend("$changes\n");

                $smtp->dataend();
                $smtp->quit;
        }else
        {
                system("date");
                print "$companyName: No change\n";
        }
# End Of File

    [download]
    I apologise ahead of time for lack of good meaningful comments and have to give credit to various sources from around the 'net for little tips here and there... like the qr thing. So the 'net owns this not me. hehe
    The file that it is reading from would be named "LensMart" or whatever you put in for company name. An example line would be...
    Acuvue###http://www.lensmart.com/scripts/ProductLens.asp/Pro dId=1/cur=1/cam=LM602###15.95
    You could put many lines in that file, but I dont really want to go through that person's site and pull up all of their individual products. Dont forget to change the readpath to wherever you are going to put the file. This works best with linux because I have prepended the second file with . to hide it, as it is really just a temp file. I dont know what windows will do in this situation.
    Ok thats enough babbling, I shall now leave it to those who are more wise.
[reply]
[d/l]
      Was wondering if anyone was able to get this code to work?
      By Kzin
[reply]

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