#!/usr/bin/perl  
use warnings;
$pro="ABCDEFGH"; 
@pro=split('',$pro);
print"\n\n Tetra words are:\n";
 $one=1; 
foreach my $item (@pro) { @tetra=@pro [0..3]; 
 $pos=$+[0]+$one;          # Line 8
 $tetra=join('',@tetra);
 print"\n $tetra  ->Starting at pos $pos\n";
 $pro =~ s/.//;
 @pro=split('',$pro);
 }
# To get the last tetra:
 $last=join('',@pro); print"\n $last\n"; # Line 15
exit;

##</code><code>##

Microsoft Windows [Version 6.1.7600]
C:\Users\x>cd desktop
C:\Users\x\Desktop>try.pl

 Tetra words are:
Use of uninitialized value in addition (+) at C:\Users\x\Desktop\try.pl
 line 8.

 ABCD  ->Starting at pos 1

 BCDE  ->Starting at pos 2

 CDEF  ->Starting at pos 2

 DEFG  ->Starting at pos 2

 EFGH 

##</code><code>##

 Tetra words are:
 ABCD  ->Starting at pos 1

 BCDE  ->Starting at pos 2

 CDEF  ->Starting at pos 3

 DEFG  ->Starting at pos 4

 EFGH  ->Starting at pos 5