I read perlfunc and all it has to say on the subject is:
'p' A pointer to a null-terminated string.
'P' A pointer to a structure (fixed-length string).

I tried using this to read the contents of a reference but all I get is fatal exceptions. How is this used in practice?

Sample code: 

use B 'svref_2object';
$rv = \"hello kitty";
$rv_obj = svref_2object( $rv );
$rv_address = B::address( $rv_obj );

$sv_any = unpack 'P4', $rv_address; # It fails here
$rv_address += 4;
$sv_refcnt = unpack 'P4', $rv_address; # or here if I just increment t
+he address
$rv_address += 4;
$sv_flags = unpack 'P4', $rv_address; # or anywhere I try using unpack
+ 'P'
printf "%08x\n%08x\n%08x\n", $sv_refcnt;

[download]

So what do I have to do to get P to work? I'd like to be able to do some runtime magic but this has me stymied.

In reply to Using pack with P and p? by diotalevi

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