Line 23: printf is not the operator to use ( Perl is not C ). Use print with a trailing newline where appropriate(or, with a recent version of Perl, say)

You'll find this ( sorta' ) works:

for (@ID,@ISIN,@SYMBOL, "\n",) 
    { 
    print  "$_:";
    }
...
[download]

That's a really ugly hack and produces many lines containing only a single colon.

Nonetheless, for part one, see printf and compare to print.

For part two, writing a coherent set of suggestions about the other problems (unnecessary use of arrays which you then route thru a foreach; failing to give your series of "ifs" an escape route (better, perhaps, an if, two elsifs and an else); etc.; would take more time than I have just now. [<update> Besides, muba did a fine job on most of it while I was still fiddling. </update>] Sorry, but perhaps you can infer (or read docs) how this works:

#!/usr/bin/perl
use 5.014;

sub getValue {
            my ($value, $name);  # $name is a throwaway; why?
            $_ = shift;
            ( $name, $value ) = split(/:/);
            $value =~ s/\s//g;
            return $value;
}

print "ID  SYMBOL  ISIN\n";

while (<DATA>) {
    my ($ID,$ISIN,$SYMBOL);
    if ($_ =~ m/ID:/) { 
        $ID = getValue($_); 
        $ID = $ID . ":";       # append colon removed by split
        chomp $ID;
        print $ID;
    } elsif ($_ =~ m/Symbol:/) { 
        $SYMBOL = getValue($_); 
        chomp $SYMBOL;
        $SYMBOL .= ":";        # alternate method to append colon
        print $SYMBOL;
    } elsif ($_ =~ m/ISIN:/) { 
        $ISIN = getValue($_);
        chomp $ISIN;
        print $ISIN ."\n";
    } else {
        next;
    }
}

__DATA__
                  Deleted; see careless OP's request in node below and
+, as msgd to me:
"Sorry for bothering you sir. But could you please change the data on 
+node : http://www. perlmonks.org/? displaytype= displaycode; node_id=
+976512 to : http://www. perlmonks.org/? displaytype= displaycode; nod
+e_id=991009 , appreciate it! !prod data"
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output:

ID  SYMBOL  ISIN
QYQ:LUP2L100OHM:SE0004017929
R1M:TLS2K50OHM:SE0004018539
QNF:MINILONGOMXAO:SE0003990183
QX8:ALF2K160OHM:SE0004017440
NC0:BOL2K170OHM:SE0003842137
NEV:NOK2K90OHM:SE0003843069
[download]

OP or OP's management seems to believe one can make things disappear from the internet.

Wrong. Can you spell "cache" or "waybackmachine?"

OP also seems to think I have some hold over kenosis, as evidenced by this message (verbatim), also received by me:

"kamchez says Re Re: matching strings into array from txtfile and printing on same line
 kenosis, could you please change all of the "data" to dummy data as follows, the reason is that the current data is important production data that shouldn't be online (my fault) and that my employer wants it removed asap "

could all of you please change all of the "data" to dummy data as follows, the reason is that the current data is important production data that shouldn't be online (my fault) and that my employer wants it removed asap. I would greatly appreciate the help!!! you can change all of the data to the following :

__DATA__
contract diff, generated at 2012-06-00T00:00:48
=========================================================
Reading old orderbooks from: gzip -cd < /PATH/orderbook_20120600T0000.
+txt.gz|
Reading new orderbooks from: gzip -cd < /PATH/orderbook_20120600T0002.
+txt.gz |

Modified contracts: (Total 0)
------------------------------------------
------------------------------------------

Deleted contracts: (Total 144)
------------------------------------------
 Orderbook ID: XXX
 Symbol:     DUMMY 00OXX
 ISIN:       SE000123456
 Market:     Plain Dummy SE
   ## inactivationTime: [2012-01-01T00:00:00] => [2012-01-10T00:00:00]
   ## XML/Warrant/ReimbursementDay: [2012-01-06] => [2012-01-10]
   ## XML/Warrant/LastTradedDay: [2012-01-06] => [2012-01-10]
   ## unpublicationTime: [2012-01-01T00:00:00] => [2012-01-10T00:00:00
[download]

I'm kind of partial to setting the input record separator when there is a consistent separator between records, and then it's usually possible to fashion a regex to pluck out the values from a single record:

#!/usr/bin/env perl
use Modern::Perl;

local $/ = ""; # split records on a blank line

while (<DATA>) {
    if ( m[Orderbook\ ID: \s* (.+?) \n
              \s* Symbol: \s* (.+?) \n
              \s*   ISIN: \s* (.+?) \n ]xs ){
        say "$1:$3:$2";

        # comment the previous line and uncomment the next three if yo
+u really
        # want to strip whitespace from your values, unlike your first
        # example

        # my $l = "$1:$3:$2";
        # $l =~ s/\s+//g;
        # say $l;
    }
}

__DATA__
[Sample data removed by request of the original poster.]
[download]

Nice work, Aaron!

Try including a newline in your print statement.

That being said, I felt there were some more things about your script that could use a little clean up.

It's still not perfect though - not all incantations of the script seem to give an error message when you want it. I'll leave it as an exercise to you to find out how to solve that. Hint: check whether $ARGV[0] (or @ARGV) actually is set.

Here's another option with your data in the file data.txt:

use Modern::Perl;
use File::Slurp qw/read_file/;

my $lines;

for (read_file 'data.txt') {
    if ( /Orderbook/ .. /ISIN/ ) {
        $lines .= $_;
    }
    elsif ($lines) {
        my ( $id, $sy, $is ) =
          $lines =~ /ID:(.*)[\s\S]+Symbol:(.*)[\s\S]+ISIN:(.*)/;
        my $line = "$id:$sy:$is";
        $line =~ s/\s//g;
        say $line;
        $lines = '';
    }
}
[download]

Output:

QYQ:LUP2L100OHM:SE0004017929
R1M:TLS2K50OHM:SE0004018539
QNF:MINILONGOMXAO:SE0003990183
QX8:ALF2K160OHM:SE0004017440
NC0:BOL2K170OHM:SE0003842137
NEV:NOK2K90OHM:SE0003843069
[download]

Thank you all for taking the time to help me out! It's truly amazing how many ways there are to do something ;) I've learned a lot by reading your replies and I've cleaned up the code a little and tweaked it with the input I got from each of you. here it goes;

use strict;
use warnings;
use File::Basename;
use Text::ParseWords;

if ($#ARGV == 0) {

        open my $file, "<", $ARGV[0] or die "Couldn't open file '$ARGV
+[0]': $! \nDid you specify a valid file?";

                my ($ID,$ISIN,$SYMBOL);
                while (<$file>) {
                if ($_ =~ m/ID:/) { $ID = getValue($_); }
                if ($_ =~ m/Symbol:/) { $SYMBOL = getValue($_); }
                if ($_ =~ m/ISIN:/) {
                        $ISIN = getValue($_);
                        print "$ID:$ISIN:$SYMBOL\n";
                        }
                }

} else {
        print "You need to specify an input file \n";
        print "Usage : ".basename($0)." difffile.txt \n";
        exit;
}

sub getValue {
        $_ =~ s/\s+//g;
        my ($name, $value) = split(/:/);
        chomp($value);
        return $value;
        }
[download]

please let me know if there are any more improvements that can be done to make it more "clean" and "proper" according to "proper coding standards" ;9 Thank you all !!

QYP:SE0001234567:LUP2L80OHM
NGA:SE0001234567:SHB2K260OHM
NJQ:SE0001234567:TRE2K70OHM
NH0:SE0001234567:SKF3A190OHM
NEY:SE0001234567:NOK3A70OHM
QUA:SE0001234567:MINILONGLUPFO
QPC:SE0001234567:MINISHRTOMXOO
QP3:SE0001234567:MINISHRTOMXFO
QU9:SE0001234567:MINILONGLUPEO
P3B:SE0001234567:SWM2K240OHM
P0N:SE0001234567:ASS3A160OHM
NGF:SE0001234567:SHB3A260OHM
R1B:SE0001234567:SKF2K210OHM
QP8:SE0001234567:MINISHRTOMXKO
R1K:SE0001234567:TEL3A123OHM
P34:SE0001234567:SWE2K140OHM
NAS:SE0001234567:ASS2K180OHM
NC3:SE0001234567:BOL3A150OHM
NDD:SE0001234567:HM2L280OHM
NCX:SE0001234567:ERI3A120OHM
P2D:SE0001234567:OXS3A1300OHM
QNA:SE0001234567:MINILONGABBCO
NGV:SE0001234567:SKF2K190OHM
QPE:SE0001234567:MINISHRTOMXQO
QU7:SE0001234567:MINILONGLUPCO
[download]