c:\@Work\Perl\monks>perl -wMstrict -le
"use 5.010;
 ;;
 my @ra = (0, 0, 0);
 ;;
 my $i = 1;
 print qq{value at index $i: }, $ra[$i] || 'undef';
 print qq{value at index $i: }, $ra[$i] // 'undef';
 print qq{value at index $i: }, defined($ra[$i]) ? $ra[$i] : 'undef'
"
value at index 1: undef
value at index 1: 0
value at index 1: 0