If the array is empty, then -1 goes to -1 which cannot exist
If the array is not empty, then -1 goes to the last element (it exists)
$ perl -Mdiagnostics -e " my @f; $f[-1] = 0; "
Modification of non-creatable array value attempted, subscript -1 at -
+e line 1 (#1)
(F) You tried to make an array value spring into existence, and th
+e
subscript was probably negative, even counting from end of the arr
+ay
backwards.
Uncaught exception from user code:
Modification of non-creatable array value attempted, subscript
+ -1 at -e line 1.
$ perl -Mdiagnostics -e " my @f = 0; $f[-1] = 0; "
