This is the sort of code where you wish pass-by-reference
was more obvious to the beginning coder.
sub Merge(@) {
my @array = @_;
MergeSort (\@array, 0, $#array);
return @array;
}
sub MergeSort($$$) {
my $arrref = shift;
my $first = shift;
my $last = shift;
if ($last>$first) {
my $mid = int(($last+$first)/2);
MergeSort($arrref, $first, $mid);
MergeSort($arrref, $mid+1, $last);
my @b;
@b = ( @{$arrref}[$first..$mid], @{$arrref}[reverse($mid+1..$last)
+] );
my ($i, $j, $k) = (0, $last-$first, $first);
for (; $k<=$last; $k++) {
$arrref->[$k] = ($b[$i]<$b[$j]) ? $b[$i++] : $b[$j--];
}
}
}
As others have stated nesting subroutines Doesn't Do What
You Expect. =) The enclosure method is nice but you should
get used to passing references where you can. In this case
Merge makes a copy of the data and then passes a reference
on to MergeSort to do with as it pleases. Each recursive
level of MergeSort passes the reference down to the next level.
Neat and simple.
HTH
--
$you = new YOU;
honk() if $you->love(perl)
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