I made sure to reply without looking at other responses.

@a = ("a", 1, "b", 2, "c", 3);
$i = 0;
grep($foo{$_} = $a[$#a - $i++], @a);

# for each element $_ in @a
# set $foo{$_} to the element OPPOSITE $_ in the array
# %foo = (
#   a => 3, 1 => 'c', b => 2,
#   2 => 'b', c => 1, 3 => 'a',
# )

print $foo{"c"}, "\n";  # 1
[download]

As far as an easier way to populate the hash, I'd do:

@foo{@a} = reverse @a;
[download]

_____________________________________________________
Jeff[japhy]Pinyan: Perl, regex, and perl hacker.
s++=END;++y(;-P)}y js++=;shajsj<++y(p-q)}?print:??;