Please see my edited code above
Please have a look at How do I change/delete my post?, in particular, "It is uncool to update a node in a way that renders replies confusing or meaningless". But luckily I still had your original code sitting around:
sub get_max_index {
my $i, $imax;
for ($i=0; $i<@_; $i++)
{
$imax=$i if ($_[$i] > $_[$imax]);
}
return $imax;
}
my @arr = (1..10);
my $ans = get_max_index(@arr);
Other than that, Paladin has already pointed out the issue with the second my declaration inside the loop in your updated code. I just wanted to add that in general, one should not combine my with an if statement modifier, as its behavior is undefined (see Statement Modifiers).