Some ways (by no means every possible way) to do what I understand you to want done:
>perl -wMstrict -le
"my @t = ('A' .. 'M');
;;
my @ra = @t;
print qq{@ra};
;;
my $start = 5;
for my $i (0 .. $#ra) {
if ($i < $start) {
$ra[$i] = 'N';
}
}
print qq{@ra \n};
;;
@ra = @t;
print qq{@ra};
;;
my $end = ($start <= $#ra) ? $start - 1 : $#ra;
for my $i (0 .. $end) {
$ra[$i] = 'N';
}
print qq{@ra \n};
;;
@ra = @t;
print qq{@ra};
$_ = 'N' for @ra[ 0 .. $end ];
print qq{@ra \n};
;;
@ra = @t;
print qq{@ra};
@ra[ 0 .. $end ] = ('N') x ($end + 1);
print qq{@ra \n};
"
A B C D E F G H I J K L M
N N N N N F G H I J K L M
A B C D E F G H I J K L M
N N N N N F G H I J K L M
A B C D E F G H I J K L M
N N N N N F G H I J K L M
A B C D E F G H I J K L M
N N N N N F G H I J K L M