regex help!

[Geoff Cox]

Hello,

I am trying to extract email addresses from about 1000 htm files.

So far am trying

if ($line =~ /Mailto:(.*)"/ {
print OUT ("$1 \n");

where the line is

<a href="mailto:fred@aol.com"

problem is with the " after the email address and the "greedy" regex
characteristic which finds other " further along the line ...

can I stop at the first " mark?

Cheers

Geoff

[Andreas Kahari]

In article <lle5mvgf13133a618g0s3h560bpi1c535e@4ax.com>, Geoff Cox wrote:

> Hello,
>
> I am trying to extract email addresses from about 1000 htm files.

E-mail address harvesting on your spare time, are you?

> if ($line =~ /Mailto:(.*)"/ {
> print OUT ("$1 \n");

[cut]

> problem is with the " after the email address and the "greedy" regex
> characteristic which finds other " further along the line ...

Read the perlre manual about changing the "greediness" of a
quantifier with "?".


--
Andreas Kähäri

[Michael Budash]

In article <lle5mvgf13133a618g0s3h560bpi1c535e@4ax.com>,
Geoff Cox <geoff.cox@blueyonder.co.uk> wrote:

> Hello,
>
> I am trying to extract email addresses from about 1000 htm files.
>
> So far am trying
>
> if ($line =~ /Mailto:(.*)"/ {
> print OUT ("$1 \n");
>
> where the line is
>
> <a href="mailto:fred@aol.com"
>
> problem is with the " after the email address and the "greedy" regex
> characteristic which finds other " further along the line ...
>
> can I stop at the first " mark?

/Mailto:(.*?)"/

you know that won't match your example don't you? unless you add the 'i'
flag (for 'i'gnore case):


/Mailto:(.*?)"/i

hth-

--
Michael Budash

[Geoff Cox]

On Sat, 13 Sep 2003 07:33:31 GMT, Michael Budash <mbudash@sonic.net>
wrote:

>/Mailto:(.*?)"/
>
>you know that won't match your example don't you? unless you add the 'i'
>flag (for 'i'gnore case):

Michael,

Thanks for the help - following code works now but I get the error
message "uninitialized value in string ne at ... the line with a **
below - do you knwo why?

Cheers

Geoff

use warnings;
use strict;

use File::Find;

open (OUT, ">>out");

my $dir = 'c:/atemp1/directory';

find ( sub {

open (IN, "$_");
my $line = <IN>;
** while ($line ne "") {
if ($line =~ /Mailto:(.*?)"/i) {
print OUT ("$1 \n");
}
$line = <IN>;
}

}, $dir);

close (OUT);

>
>/Mailto:(.*?)"/i
>
>hth-

[Andreas Kahari]

In article <sfk5mvo202ccnl1b8tjv634fut1qvdo1nf@4ax.com>, Geoff Cox wrote:
[cut]

> Thanks for the help - following code works now but I get the error
> message "uninitialized value in string ne at ... the line with a **
> below - do you knwo why?

[cut]

> open (IN, "$_");
> my $line = <IN>;
> ** while ($line ne "") {
> if ($line =~ /Mailto:(.*?)"/i) {
> print OUT ("$1 \n");

[cut]


What happens at the end of a file? Well, <IN> will give you an
undefined value. This will also happen if the open() call failed.


--
Andreas Kähäri

[Geoff Cox]

On Sat, 13 Sep 2003 08:21:39 +0000 (UTC), Andreas Kahari
<ak+usenet@freeshell.org> wrote:

>In article <sfk5mvo202ccnl1b8tjv634fut1qvdo1nf@4ax.com>, Geoff Cox wrote:
>[cut]

>> Thanks for the help - following code works now but I get the error
>> message "uninitialized value in string ne at ... the line with a **
>> below - do you knwo why?

>[cut]

>> open (IN, "$_");
>> my $line = <IN>;
>> ** while ($line ne "") {
>> if ($line =~ /Mailto:(.*?)"/i) {
>> print OUT ("$1 \n");

>[cut]
>
>
>What happens at the end of a file? Well, <IN> will give you an
>undefined value. This will also happen if the open() call failed.

Andreas,

ah! well the open call works so must be the end of file part - is
there a better way than using while ($line ne "" ) ? eof?

Geoff

[Andreas Kahari]

In article <28l5mvovmurpbjk33goktp83ee2iv9e06f@4ax.com>, Geoff Cox wrote:

> On Sat, 13 Sep 2003 08:21:39 +0000 (UTC), Andreas Kahari
><ak+usenet@freeshell.org> wrote:

>>In article <sfk5mvo202ccnl1b8tjv634fut1qvdo1nf@4ax.com>, Geoff Cox wrote:

[cut]

>>> open (IN, "$_");
>>> my $line = <IN>;
>>> ** while ($line ne "") {
>>> if ($line =~ /Mailto:(.*?)"/i) {
>>> print OUT ("$1 \n");

>>[cut]
>>
>>
>>What happens at the end of a file? Well, <IN> will give you an
>>undefined value. This will also happen if the open() call failed.

>
> Andreas,
>
> ah! well the open call works so must be the end of file part - is
> there a better way than using while ($line ne "" ) ? eof?

Yes, a much much better way:

while(defined($line = <IN>)) {
... code ...
}

And personally I would say

open(IN, $_) or die "Failed in open(): $!";


Cheers,
Andreas

--
Andreas Kähäri

[Geoff Cox]

On Sat, 13 Sep 2003 08:39:03 +0000 (UTC), Andreas Kahari
<ak+usenet@freeshell.org> wrote:

>Yes, a much much better way:
>
> while(defined($line = <IN>)) {
> ... code ...
> }
>
>And personally I would say
>
> open(IN, $_) or die "Failed in open(): $!";

will use both - thanks!

Geoff

>
>
>Cheers,
>Andreas

[Tad McClellan]

Geoff Cox <geoff.cox@blueyonder.co.uk> wrote:

> On Sat, 13 Sep 2003 08:39:03 +0000 (UTC), Andreas Kahari
><ak+usenet@freeshell.org> wrote:

>> while(defined($line = <IN>)) {

I like this better:

while ( my $line = <IN> ) {

>> ... code ...
>> }
>>
>>And personally I would say
>>
>> open(IN, $_) or die "Failed in open(): $!";

>
> will use both - thanks!

If you read the docs for the function that you used, then you
would have already known to check open()'s return value.

(there is a general-purpose lesson there...)


perldoc -f open

Open returns nonzero upon success, the undefined value otherwise.
...
When opening a file, it's usually a bad idea to continue normal execution
if the request failed, so C<open> is frequently used in connection with
C<die>. Even if C<die> won't do what you want (say, in a CGI script,
where you want to make a nicely formatted error message (but there are
modules that can help with that problem)) you should always check
the return value from opening a file.

--
Tad McClellan SGML consulting
[email]tadmc@augustmail.com[/email] Perl programming
Fort Worth, Texas

[Eric J. Roode]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Geoff Cox <geoff.cox@blueyonder.co.uk> wrote in
news:lle5mvgf13133a618g0s3h560bpi1c535e@4ax.com:

> I am trying to extract email addresses from about 1000 htm files.
>
> So far am trying
>
> if ($line =~ /Mailto:(.*)"/ {
> print OUT ("$1 \n");
>
> where the line is
>
> <a href="mailto:fred@aol.com"
>
> problem is with the " after the email address and the "greedy" regex
> characteristic which finds other " further along the line ...
>
> can I stop at the first " mark?

Change your thinking a bit. Instead of matching "Mailto:" followed by as
many characters as possible followed by a quote, match "Mailto:" followed
by as many non-quote characters as possible followed by a quote:

if ($line =~ /Mailto:([^"]*)"/)

Also consider making it case-insensitive with the i modifier.

- --
Eric
$_ = reverse sort $ /. r , qw p ekca lre uJ reh
ts p , map $ _. $ " , qw e p h tona e and print

-----BEGIN PGP SIGNATURE-----
Version: PGPfreeware 7.0.3 for non-commercial use <http://www.pgp.com>

iQA/AwUBP2MoO2PeouIeTNHoEQIdtACgxV2WliWoH07gZaS39JHGdb 1q+wAAn1f6
oXom0J4O85KppYwOysICYuZs
=yU+G
-----END PGP SIGNATURE-----

[Geoff Cox]

On Sat, 13 Sep 2003 09:22:06 -0500, "Eric J. Roode"
<REMOVEsdnCAPS@comcast.net> wrote:

>Change your thinking a bit. Instead of matching "Mailto:" followed by as
>many characters as possible followed by a quote, match "Mailto:" followed
>by as many non-quote characters as possible followed by a quote:
>
> if ($line =~ /Mailto:([^"]*)"/)

Thanks Eric - will give it a try...

Cheers

Geoff

>
>Also consider making it case-insensitive with the i modifier.