This should do what you're looking for:

#!/usr/bin/perl

use strict;
use warnings;

my $data = "123456789";

# get two digits, and replace them with two digits
# and a space (globally repeating until the end of
# the string)

$data =~ s/(\d{2})/$1 /g;

print $data, "\n";
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jd

Yeah.. this is i am looking for....

Thank you very much....
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You're welcome!

Where do you want *them* to go today?

What have you tried? you could use split with a little mucking about, but it would be easier to use a regular expression.

does the look-behind count as mucking around? ;) (as opposed to having to shift off the first blank element)

perl -le 'print join ":", split /(?<=\d\d)(\d\d)/, "123456789"'
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oh, i guess that doesn't work for '123' ... back to a little more mucking:

perl -le 'print join ":", grep {length} split /(\d\d)/, "123456789"'
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print +(join ' ', grep {/\d/} split /(..)/), "\n";
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was what I had in mind, although the autoflush trick (--$|, see $| pre and post increment and deincrement behavior) is kinda cute too ;).

Update: added link

---

DWIM is Perl's answer to Gödel

Currently, I am dump all the input data into array, then split it for 
+each two variables. I think that is not a good method.
Do you know the simple solution ?
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Show us your current code and we will comment on that. That way we have some idea of what you know already.

---

DWIM is Perl's answer to Gödel

I would do it like this. You'll notice that it's similar to a previous solution, but takes the extra step of intentionally failing to match at the end of the string. That way you don't end up with "89_" (where I'm using _ to signify trailing space).

In my example, I'm intentionally printing a '#' at the end of each string to demonstrate that there's no extra whitespace being appended to the end of the string.

use strict;
use warnings;

my @data = ( '12345678', '123456789' );


foreach my $number ( @data ) {
    my $modified = $number;
    $modified =~ s/(\d{2})(?!$)/$1 /g;
    print "$modified#\n";
}
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You could also use substr and loop through until you run out of characters.

$ echo "12345678
123456789" | perl -lne'print join q[ ], unpack q[(a2)*], $_'
12 34 56 78
12 34 56 78 9
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Or without even Perl . . .

$ irb -r enumerator
irb(main):001:0> "12345678".split(//).enum_slice( 2 ).inject( [] ) { |
+a,x| a << x.join( "" ) }.join( " " ) 
=> "12 34 56 78"
irb(main):002:0> "123456789".split(//).enum_slice( 2 ).inject( [] ) { 
+|a,x| a << x.join( "" ) }.join( " " )
=> "12 34 56 78 9"
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Update: Or maybe a little more concisely:

irb(main):011:0> "12345678".split(//).enum_slice( 2 ).map {|a| a.join(
+"")}.join(" ")
=> "12 34 56 78"
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perl -le 'print $1 while ($ARGV[0] =~ s/(.{1,2})(.*)/$2/g);' "12345678
+9"

perl -le '$c=-2; print while $_ = substr $ARGV[0], $c+=2, 2;' "1234567
+89"
# or
perl -le 'while ($_ = substr $ARGV[0], $c, 2) { print; $c+=2 };' "1234
+56789"

perl -le '@_=reverse split//, $ARGV[0]; while (@_) {print join"", (pop
+@_, pop@_);}' "123456789"

perl -le '@_=split//, $ARGV[0]; while (@_) {print join"", (shift@_, sh
+ift@_);}' "123456789"

perl -le '@_=split//, $ARGV[0]; while (@_) {print join "", splice @_, 
+0, 2}' "123456789"

perl -le '@_ = split //,$ARGV[0]; splice @_, $_, 2, $_[$_].$_[$_+1] fo
+r 0..$#_/2; print "@_"' "123456789"

# some alternatives to ones already posted..
 perl -le 'print for grep /./, split /(..)/, $ARGV[0]' "123456789"

perl -le 'print for unpack "(Z2)*", $ARGV[0]' "123456789"

# probably the fastest
echo 123456789 | perl -nle 'print for /(..?)/g'
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