Hello smittypaddler,

Some notes:

1. Obligatory reference on autovivification: Autovivification: What is it and why do I care? by Uri Guttman
2. $#{$array} can be written more simply without the braces: $#$array
3. The CPAN module autovivification can be used to disable this behaviour:

   use strict;
   use warnings;
   no  autovivification;
   
   my $array;
   
   warn sprintf 'array is%s defined', defined $array ? '' : ' not';
   warn         '$#$array is ',             $#$array;
   warn sprintf 'array is%s defined', defined $array ? '' : ' not';
   [download]

   Output:

   13:28 >perl 1999_SoPW.pl
   array is not defined at 1999_SoPW.pl line 7.
   Can't use an undefined value as an ARRAY reference at 1999_SoPW.pl lin
   +e 8.
   
   13:28 >
   [download]

Hope that’s of interest,