>perl -wMstrict -le
"my @ra = qw(a b c d);
 print qq{@ra};
 for my $elem (@ra) {
   print ++$elem;
   }
 print qq{@ra};
 ;;
 for my $elem (qw(a b c d)) {
   print ++$elem;
   }
"
a b c d
b
c
d
e
b c d e
Modification of a read-only value attempted at -e line 1.