[19525] in Perl-Users-Digest
Perl-Users Digest, Issue: 1720 Volume: 10
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Sun Sep 9 18:10:26 2001
Date: Sun, 9 Sep 2001 15:10:10 -0700 (PDT)
From: Perl-Users Digest <Perl-Users-Request@ruby.OCE.ORST.EDU>
To: Perl-Users@ruby.OCE.ORST.EDU (Perl-Users Digest)
Message-Id: <1000073410-v10-i1720@ruby.oce.orst.edu>
Content-Type: text
Perl-Users Digest Sun, 9 Sep 2001 Volume: 10 Number: 1720
Today's topics:
printing all even || odd numbers from array <ds@ss.com>
Re: printing all even || odd numbers from array <tony_curtis32@yahoo.com>
Re: printing all even || odd numbers from array <ds@ss.com>
Re: printing all even || odd numbers from array (Sam Holden)
Re: printing all even || odd numbers from array <godzilla@stomp.stomp.tokyo>
Re: printing all even || odd numbers from array <krahnj@acm.org>
Re: printing all even || odd numbers from array <philip@zaynar.demon.co.uk>
Re: printing all even || odd numbers from array <uwe@richard-schneider.de>
Re: printing all even || odd numbers from array (Randal L. Schwartz)
Re: printing all even || odd numbers from array <bart.lateur@skynet.be>
Redirect eval output to socket problem <javaneese@hotmail.com>
Re: Redirect eval output to socket problem <bart.lateur@skynet.be>
Re: Reverse DNS lookup (David Efflandt)
Re: Reverse DNS lookup <godzilla@stomp.stomp.tokyo>
Digest Administrivia (Last modified: 6 Apr 01) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: Sun, 09 Sep 2001 17:35:48 GMT
From: GunneR <ds@ss.com>
Subject: printing all even || odd numbers from array
Message-Id: <jcupptcchdq1s9fchguv2bstsiq792bhb1@4ax.com>
Just trying to print out all even numbers (not even elements) from an
array. Someone told me to use the % operator but I cant seem to get it
working:
#perl
@array1 = qw(1 2 3 4 5 6);
$b = 0;
foreach (@array1) {
if (! $array1[$b] % 2) {
print "$array1[$b]\n";
$b++;
}
}
Want it to print "2 4 6"
Any advice?
Thanks!
------------------------------
Date: Sun, 09 Sep 2001 12:57:38 -0500
From: Tony Curtis <tony_curtis32@yahoo.com>
Subject: Re: printing all even || odd numbers from array
Message-Id: <87y9nojlgt.fsf@limey.hpcc.uh.edu>
>> On Sun, 09 Sep 2001 17:35:48 GMT,
>> GunneR <ds@ss.com> said:
> Just trying to print out all even numbers (not even
> elements) from an array. Someone told me to use the %
> operator but I cant seem to get it working:
> @array1 = qw(1 2 3 4 5 6);
> $b = 0;
> foreach (@array1) {
> if (! $array1[$b] % 2) {
> print "$array1[$b]\n";
> $b++;
> }
> }
> Want it to print "2 4 6"
This looks awfully C-like. In general you don't need to
use subscripts in perl, you simply iterate over the
elements rather than each index:
@a = qw(1 2 3 4 5 6);
foreach my $e (@a) {
print "$e " if $e % 2 == 0;
}
print "\n";
hth
t
--
Yes way! Mmmmkay?
------------------------------
Date: Sun, 09 Sep 2001 17:50:46 GMT
From: GunneR <ds@ss.com>
Subject: Re: printing all even || odd numbers from array
Message-Id: <ebvppt4mom86gapbdjvak64h7t637te1p1@4ax.com>
Never mind! :)
#perl
@array1 = qw(1 2 3 4 5 6);
$b = 0;
foreach (@array1) {
if (($array1[$b] % 2) == 0) {
print "$array1[$b]\n";
$b++;
next;
}
else { $b++; next;
}
}
Never Perl on an empty stomach....
On Sun, 09 Sep 2001 17:35:48 GMT, GunneR <ds@ss.com> wrote:
>Just trying to print out all even numbers (not even elements) from an
>array. Someone told me to use the % operator but I cant seem to get it
>working:
>
>#perl
>
>@array1 = qw(1 2 3 4 5 6);
>
>$b = 0;
>
>foreach (@array1) {
> if (! $array1[$b] % 2) {
> print "$array1[$b]\n";
> $b++;
> }
>}
>
>Want it to print "2 4 6"
>
>Any advice?
>
>Thanks!
------------------------------
Date: 9 Sep 2001 18:10:45 GMT
From: sholden@pgrad.cs.usyd.edu.au (Sam Holden)
Subject: Re: printing all even || odd numbers from array
Message-Id: <slrn9pnc55.8ih.sholden@pgrad.cs.usyd.edu.au>
On Sun, 09 Sep 2001 17:50:46 GMT, GunneR <ds@ss.com> wrote:
>Never mind! :)
>
>#perl
>
>@array1 = qw(1 2 3 4 5 6);
>
>$b = 0;
>
>foreach (@array1) {
> if (($array1[$b] % 2) == 0) {
> print "$array1[$b]\n";
> $b++;
> next;
> }
> else { $b++; next;
> }
>}
Maybe you should read the docs on what foreach does... That is one
strange way to code a loop....
There's some unnecesary cut-n-paste code as well...
------------------------------
Date: Sun, 09 Sep 2001 12:15:24 -0700
From: "Godzilla!" <godzilla@stomp.stomp.tokyo>
Subject: Re: printing all even || odd numbers from array
Message-Id: <3B9BBFCC.3CF57F57@stomp.stomp.tokyo>
GunneR wrote:
(snipped)
> Just trying to print out all even numbers (not even elements) from an
> array. Someone told me to use the % operator but I cant seem to get it
> working:
#!perl
@array1 = qw(1 2 3 4 5 6);
for (@array1)
{
if (substr ($_, -1, 1) =~ /[02468]/)
{ print $_; }
}
exit;
Godzilla!
--
Sun Sep 9 10:11:26 2001 - RESTRICTED FILE REDIRECT:
- DNS: - IPA: 207.225.221.67
- System:
- Redirect URL: /default.ida
------------------------------
Date: Sun, 09 Sep 2001 19:43:27 GMT
From: "John W. Krahn" <krahnj@acm.org>
Subject: Re: printing all even || odd numbers from array
Message-Id: <3B9BC6D8.6D60EE56@acm.org>
GunneR wrote:
>
> Just trying to print out all even numbers (not even elements) from an
> array. Someone told me to use the % operator but I cant seem to get it
> working:
>
> #perl
>
> @array1 = qw(1 2 3 4 5 6);
>
> $b = 0;
>
> foreach (@array1) {
> if (! $array1[$b] % 2) {
> print "$array1[$b]\n";
> $b++;
> }
> }
>
> Want it to print "2 4 6"
The Perl way:
#perl -w
use strict;
my @array1 = qw(1 2 3 4 5 6);
foreach my $b ( @array1 ) {
unless ( $b % 2 ) {
print "$b\n";
}
}
__END__
The C way:
#perl -w
use strict;
my @array1 = qw(1 2 3 4 5 6);
for ( my $b = 0; $b < @array1; ++$b ) {
if ( ! $array1[$b] % 2 ) {
print "$array1[$b]\n";
}
}
__END__
John
--
use Perl;
program
fulfillment
------------------------------
Date: Sun, 9 Sep 2001 21:00:18 +0100
From: Philip Taylor <philip@zaynar.demon.co.uk>
Subject: Re: printing all even || odd numbers from array
Message-Id: <aeG4tFASp8m7EwGy@zaynar.demon.co.uk>
In article <3B9BC6D8.6D60EE56@acm.org>, "John W. Krahn" <krahnj@acm.org>
writes
>GunneR wrote:
>>
>> Just trying to print out all even numbers (not even elements) from an
>> array. Someone told me to use the % operator but I cant seem to get it
>> working:
>
>The Perl way:
>
>#perl -w
>use strict;
>
>my @array1 = qw(1 2 3 4 5 6);
>
>foreach my $b ( @array1 ) {
> unless ( $b % 2 ) {
> print "$b\n";
> }
>}
Or with less lines (and less understandability):
my @array1 = qw(1 2 3 4 5 6);
print grep !($_&1), @array1;
__END__
--
Philip Taylor
philip @ zaynar . demon . co . uk
http://robowarriors.ultrastore.com/legoworld.shtml
-- If the Earth was made of Lego...
------------------------------
Date: Sun, 09 Sep 2001 22:11:51 +0200
From: Uwe Schneider <uwe@richard-schneider.de>
To: GunneR <ds@ss.com>
Subject: Re: printing all even || odd numbers from array
Message-Id: <3B9BCD07.63469932@richard-schneider.de>
GunneR wrote:
>
> Just trying to print out all even numbers (not even elements) from an
> array. Someone told me to use the % operator but I cant seem to get it
> working:
>
> #perl
>
> @array1 = qw(1 2 3 4 5 6);
>
> $b = 0;
>
> foreach (@array1) {
> if (! $array1[$b] % 2) {
> print "$array1[$b]\n";
> $b++;
> }
> }
>
> Want it to print "2 4 6"
What's wrong with grep()?
#!/usr/bin/perl
use strict;
my @ary = qw(1 2 3 4 5 6);
my @bry = grep( $_ % 2 == 0,@ary);
print join(" ",@bry),"\n";
U.
--
Uwe Schneider | Telefon +49 7251 / 82587
Karlsdorfer Str. 31 | Mail pi@richard-schneider.de
DE-76646 Bruchsal | http://www.richard-schneider.de/uwe
Linux - OS al dente!
------------------------------
Date: 09 Sep 2001 13:21:54 -0700
From: merlyn@stonehenge.com (Randal L. Schwartz)
Subject: Re: printing all even || odd numbers from array
Message-Id: <m1g09wnmhp.fsf@halfdome.holdit.com>
>>>>> "GunneR" == GunneR <ds@ss.com> writes:
GunneR> @array1 = qw(1 2 3 4 5 6);
[...]
GunneR> Want it to print "2 4 6"
for (0..10) {
my @array1 = (1..$_);
print "$_: >@array1[map 1+2*$_, 0..($#array1-1)/2]<\n";
}
results in...
0: ><
1: ><
2: >2<
3: >2<
4: >2 4<
5: >2 4<
6: >2 4 6<
7: >2 4 6<
8: >2 4 6 8<
9: >2 4 6 8<
10: >2 4 6 8 10<
--
Randal L. Schwartz - Stonehenge Consulting Services, Inc. - +1 503 777 0095
<merlyn@stonehenge.com> <URL:http://www.stonehenge.com/merlyn/>
Perl/Unix/security consulting, Technical writing, Comedy, etc. etc.
See PerlTraining.Stonehenge.com for onsite and open-enrollment Perl training!
------------------------------
Date: Sun, 09 Sep 2001 21:25:23 GMT
From: Bart Lateur <bart.lateur@skynet.be>
Subject: Re: printing all even || odd numbers from array
Message-Id: <a8nnptsuaifesk1p3sk1v1ke3bjnkas0pg@4ax.com>
GunneR wrote:
>$b = 0;
>
>foreach (@array1) {
> if (($array1[$b] % 2) == 0) {
> print "$array1[$b]\n";
> $b++;
> next;
> }
> else { $b++; next;
> }
>}
Even with such an awkward loop, you can still improve on the neatness of
the code:
$b = 0;
foreach (@array1) {
if (($array1[$b] % 2) == 0) {
print "$array1[$b]\n";
}
} continue {
$b++;
}
but making $b the loop variable sounds like a better idea:
foreach my $b (0 .. $#array1) {
if (($array1[$b] % 2) == 0) {
print "$array1[$b]\n";
}
}
Well alright, the perlish way would be to recognise the fact that in
such a foreach loop, the loop variable gets set to an alias of each item
in turn. The default loop variable is $_. So:
$b = 0;
foreach (@array1) {
if ($_ % 2) == 0) {
print "$_\n";
}
} continue {
$b++;
}
(Perhaps you still have a use for that $b?)
--
Bart.
------------------------------
Date: Sun, 09 Sep 2001 20:04:26 GMT
From: Daniel <javaneese@hotmail.com>
Subject: Redirect eval output to socket problem
Message-Id: <3B9BCA66.2E302E55@hotmail.com>
Hi all pro's!
I have a problem with redirecting the output from eval to a socket (NS)
A code example that shows what I mean:
######################
$command = "print \"this text wants to be printed on the socket NS\"";
print NS "line one\n";
eval($command); # I want to redirect the output from eval to NS...
print NS "line two\n";
######################
the example prints "line one" and "line two" to the socket NS but the
output from eval comes to STDOUT.
I have tried several ways of redirection but obviosly I make something
wrong... arghhh?%!#
How to do to redirect the output from eval to the socket NS?
All help would be higly appreciated!
Thanks in advance,
Daniel
------------------------------
Date: Sun, 09 Sep 2001 21:37:23 GMT
From: Bart Lateur <bart.lateur@skynet.be>
Subject: Re: Redirect eval output to socket problem
Message-Id: <k7onptggbs4sc9uii3clkgskq15ee6pfg6@4ax.com>
Daniel wrote:
>$command = "print \"this text wants to be printed on the socket NS\"";
>print NS "line one\n";
>eval($command); # I want to redirect the output from eval to NS...
>print NS "line two\n";
>
>the example prints "line one" and "line two" to the socket NS but the
>output from eval comes to STDOUT.
Does
select NS;
do any good?
--
Bart.
------------------------------
Date: Sun, 9 Sep 2001 16:19:08 +0000 (UTC)
From: efflandt@xnet.com (David Efflandt)
Subject: Re: Reverse DNS lookup
Message-Id: <slrn9pn5jr.p2b.efflandt@typhoon.xnet.com>
On Sun, 9 Sep 2001 11:46:22 +0100, Gareth Horth <Gareth@Horth.F9.co.uk> wrote:
> Hi,
>
> How can I do a reverse DNS lookup from a perl script?
> If I do 'whois 1.2.3.4' on the CGI server it doesn't find a match - but when
> I do the same on my computer it works.
> Is there another way to do the lookup?
This is not a Perl question if it is a shell command and is not a DNS
question because whois will not tell you the hostname for an IP. whois
_might_ tell you who owns the IP block and maybe what domain name and
nameservers are used for it (if any).
It is possible that whois on the webserver is a different path/version or
not configured with a default host for looking up IP's. See 'man whois'
or what whois returns with no parameters. Examples for IP range lookup:
whois (Unix): whois -h whois.arin.net 1.2.3.4
fwhois (Linux): whois 1.2.3.4@whois.arin.net
But you also want to end any shell command with 2>&1 so you can see any
error message (whois is slow lately and may tend to timeout in CGI).
--
David Efflandt - All spam is ignored - http://www.de-srv.com/
http://www.autox.chicago.il.us/ http://www.berniesfloral.net/
http://cgi-help.virtualave.net/ http://hammer.prohosting.com/~cgi-wiz/
------------------------------
Date: Sun, 09 Sep 2001 12:35:50 -0700
From: "Godzilla!" <godzilla@stomp.stomp.tokyo>
Subject: Re: Reverse DNS lookup
Message-Id: <3B9BC496.BF298AE7@stomp.stomp.tokyo>
Gareth Horth wrote:
> How can I do a reverse DNS lookup from a perl script?
> If I do 'whois 1.2.3.4' on the CGI server it doesn't find a match - but when
> I do the same on my computer it works.
> Is there another way to do the lookup?
use Socket;
$ENV{REMOTE_HOST} = gethostbyaddr (inet_aton ($ENV{REMOTE_ADDR}), AF_INET);
Godzilla!
------------------------------
Date: 6 Apr 2001 21:33:47 GMT (Last modified)
From: Perl-Users-Request@ruby.oce.orst.edu (Perl-Users-Digest Admin)
Subject: Digest Administrivia (Last modified: 6 Apr 01)
Message-Id: <null>
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------------------------------
End of Perl-Users Digest V10 Issue 1720
***************************************
