I am unable to duplicate your problem with my perl v5.16.3. I can suggest several improvements to your code.

Always use strict and warnings.

Use of printf with only a format is confusing. Use print

Your math is unnecessarily complicated. 

use strict;
use warnings;
use POSIX qw(floor);
my @PC1=(58,50,42,34,26,18,10,2,
      60,52,44,36,28,20,12,4,
      62,54,46,38,30,22,14,6,
      64,56,48,40,32,24,16,8,
      57,49,41,33,25,17,9,1,
      59,51,43,35,27,19,11,3,
      61,53,45,37,29,21,13,5,
      63,55,47,39,31,23,15,7);

my @parr=('0','M','0','A','0','I','0','L');
print $parr[floor( $PC1[$_]/8 )], "\n" for (0..63);

[download]

My use of 'floor' is not strictly necessary in this case, but is recommended for the reason explained in int.

In reply to Re: Use of uninitialized value within by BillKSmith
in thread Use of uninitialized value within by gary16

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