Perl

Robust scripts

All scripts should start with the following:

use strict;
use warnings;
use utf8;
use autodie;

Only remove one or more of the above if you really know what you are doing.

It is also a good idea to define a minimum Perl version, e.g. to require Perl 5.14 or above:

use v5.14;

More readable names for common variables (e.g. $/ can be referred to as $INPUT_RECORD_SEPARATOR) can be created with:

use English;

Although used interchangeably, technically a list is the collection of elements whereas an array is the variable that points to the list.
$#array contains the last element index of the array. Since arrays are zero-indexed, the size of the array is $#array + 1.
Negative array indices start from the end of the list, so the last element can be accessed as $array[-1].