I recommend that you pass the value as an argument

What I was wanting to do was to pass the actual string as the argument.
It didn't really occur to me that doing that would be such a problem. I thought that people would be able to show me that this could be achieved with little fuss. (I was wrong ;-)
What I was interested in doing is easily demonstrated in the following script, where I've used the code that you supplied, but have replaced the last line with 2 lines: 

use strict;
use warnings;
my $template = 'D<';
my $nv = 2.4;
my $p = pack $template, $nv;


# I'm running this script on perl-5.34.0
# with nvtype of 'long double'.
# I want to see the result of perl-5.34.0
# with nvtype of 'double' unpacking $p :

my $perl = "C:/perl-5.34.0/bin/MSWin32-x64-multi-thread/perl.exe";
system $perl, '-wle', 'print unpack("H*", $p)';

[download]
If that DWIMmed, it would output : 
9a999999999999990040000000000000

[download]
but, of course, all that it emits is the warning: 
Use of uninitialized value $_ in print at -e line 1.

[download]
Sure, I could take a leaf out of your book and alter my last line to: 
system $perl, '-wle', 'print $ARGV[0]', unpack('H*', $p);

[download]
But that unpack('H*', $p) is being evaluated by the 'long double' build of perl.
I wanted to see what happened when it was evaluated by my 'double' build of perl-5.34.0.
I've since accomplished this by other means.

Cheers,
Rob

In reply to Re^2: pack() returns an unusable string by syphilis
in thread pack() returns an unusable string by syphilis

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