in reply to Passing values in a hash to a subroutine:

in subroutines, @_ is the array of arguments passed to the subroutine -- $_ is not related to @_ -- specificly, 
$_ isn't $_[0]

$_[0] is the first element of @_

Compare to $a, @a, and $a[0]

[download]
Does this make sense?

In Section Seekers of Perl Wisdom