use warnings;
use strict;
use List::MoreUtils qw(firstidx);

my @fsg = (1, 2, 4, 5, qw(A B C));

printf "item with index %i in list is B\n", firstidx { $_ eq 'B' } @fsg;
printf "item with index %i in list is 2\n", firstidx { $_ eq 2 } @fsg;

__END__

item with index 5 in list is B
item with index 1 in list is 2