Hi PerlMonks,

I think it might be a very silly question to ask but I am at my wit's end to find the solution. I am interested to produce the first tetra-word (ABCD) from a long string (ABCDEFGH), then to delete the first letter from the string and get the tetra word (BCDE) along with its starting position. I have written a script  try.pl using foreach LOOP which shows the tetra words but starting positions for tetra-word CDEF and DEFG are wrong. Moreover, the loop does not show the last tetra-word i.e. EFGH. So, after the loop I have written the code in line 15 to get the last tetra-word. Can I expect a better code to get all the tetra words i.e. ABCD,BCDE,CDEF,DEFG,EFGH with correct starting positions?

Here goes the script try.pl:

#!/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;
[download]

I have got the following wrong results in cmd:

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.p
+l
 line 8.

 ABCD  ->Starting at pos 1

 BCDE  ->Starting at pos 2

 CDEF  ->Starting at pos 2

 DEFG  ->Starting at pos 2

 EFGH
[download]

The correct results should look like:

 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
[download]