# This works.
my @ary;
@ary = split (" ",$_) while (<DATA>);
print join(" / ", @ary);

#As does this
my ($str,@ary);
@ary = split (" ",$str) while ($str=<DATA>);
print join(" / ", @ary);

# This doesnt work. (as you pointed out)
my @ary = split (" ",$_) while (<DATA>);
print join(" / ", @ary);

#Nor does this either
my (@ary);
@ary = split (" ",$str) while (my $str=<DATA>);
print join(" / ", @ary);