substr

substr lets us get any substring.It gets 3 parameters:

1. The original string
2. offset - where does the substring start
3. length - how long is the substring

(There is also a 4th parameter, to replace a substring, but let's not discuss that now.)

Even the 3rd parameter from the above list, the length, is optional. If not given it means "till the end of the string".

The 2nd parameter can be either a positive number, then it is an offset from the left-hand side of the string. (Most people would call it the beginning of the string, but I know places where strings start on the right-hand side, so let's call it "left-hand side".)

If the 2nd parameter is a negative number, then it is an offset from the right-hand side of the string. (Or, as many people would call it, from the end of the string.)

use strict;
use warnings;
use 5.010;

my $text = 'word';

say substr $text, -1;  # d
say $text;             # word

If the my $text = ''; was an empty string then substr $text, -1; will also return the empty string without giving any warning or error.

If the my $text; was undef, we would get a warning: Use of uninitialized value $text in substr at ....

chop

Another, solution is to use the chop function. It is quite naughty. I don't recommend this. Actually I think I never had a real world use of the chop function. If I am not mistaken, it is a left over from the era before chomp was added.

It removes and returns the last character of a string:

use strict;
use warnings;
use 5.010;

my $text = 'word';

say chop $text;  # d
say $text;       # wor

It could be used to extract, remove and compare the last character of a string, but I can't think of a real use case when the "remove" part is useful.

If the original text was the empty string my $text = '';, chop would return the empty string as well without giving any warning.

If the original text was undefined as in my $text; the call to chop $text; would give a warning: Use of uninitialized value $text in scalar chop at ....