=over =item $# X<$#> C<$#> used to be a variable that could be used to format printed numbers. After a deprecation cycle, its magic was removed in Perl 5.10 and using it now triggers a warning: C<$# is no longer supported>. C<$#> is also used as sigil, which, when prepended on the name of an array, gives the index of the last element in that array. my @array = ("a", "b", "c"); my $last_index = $#array; # $last_index is 2 for my $i (0 .. $#array) { print "The value of index $i is $array[$i]\n"; } Also see L. =back