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packing and unpacking

by ungalnanban (Pilgrim)
on Mar 12, 2010 at 09:15 UTC ( #828246=perlquestion: print w/replies, xml ) Need Help??
ungalnanban has asked for the wisdom of the Perl Monks concerning the following question:

Hi, I want to get output as 0x23400000345....
in the below example
How to get?
i tried out, but unable to get the answer

$r=0x234; $t=0x345; $y=pack('L L',$t,$r); $x1=unpack('L!',pack('P',$y)); printf("\nThe value is $x1");

I didn't get constant output


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Re: packing and unpacking
by almut (Canon) on Mar 12, 2010 at 09:40 UTC
    my $r = 0x234; my $t = 0x345; my $y = pack('L L', $t, $r); my $x1 = unpack('Q', $y); printf "\nThe value is 0x%x", $x1; # 0x23400000345

    (in case you have a 64-bit perl)

      I don't know the 64-bit Perl.
      whether you are mentioning 64-bit processor or ...?

      I am using Perl version 5.8.8

      I ran the given code It shows the following error.
      Invalid type 'Q' in unpack at line 9.

        You could also simply try

        my $x1 = $r << 32 | $t; printf "\nThe value is 0x%x", $x1; # 0x23400000345

        (though whether this works similarly depends of the build options of your perl)

        P.S.: What exactly do you need this for?  Maybe bigint or Math::BigInt would help.


        use bigint; my $r = 0x234; my $t = 0x345; my $x1 = $r << 32 | $t; print $x1->as_hex;
        From perldoc -f pack:
        Q An unsigned quad value. (Quads are available only if your system supports 64-bit integer values _and_ if Perl has been compiled to support those. Causes a fatal error otherwise.)

        (($_="Mzz ojjdloobnf jt uvy5502383")=~y~b-zg2-5c96-81~a-z0-9~s)=~s~~~s; print

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