my @unsortedArray;
foreach my $received_xml_post (@ {$xml_post_array{'data'}})
{
           push @unsortedArray, {
                                'ID' => $received_xml_post->{'ID'},
                                'Distance => $received_xml_post->{'Distance'},
                                'RouteDistance' => $received_xml_post->{'RouteDistance'}};
}

my @sortedArray = sort { $a->{RouteDistance} <=> $b->{RouteDistance || $a->{Distance} <=> $b->{Distance} } @unsortedArray;


##</code><code>##

my @unsortedArray;
foreach my $received_xml_post (@ {$xml_post_array{'data'}})
{
   push @unsortedArray, {
                         'ID' => $received_xml_post->{'ID'},
                         'Distance => $received_xml_post->{'Distance'},
                         'RouteDistance' => $received_xml_post->{'RouteDistance'}};
}

my @sortedArray = sort { if( $a->{RouteDistance} == 0) {return -1} else {$a->{RouteDistance} <=> $b->{RouteDistance} $a->{Distance} <=> $b->{Distance} } @unsortedArray;

##</code><code>##

sort {
    $a->{routedistance} && $b->{routedistance} 
    ? $a->{routedistance} <=> $b->{routedistance}
    : $a->{distance} <=> $b->{distance}
} @ar;

##</code><code>##

#!/usr/bin/perl
use warnings;
use strict;

my @unsorted_array = (	{ ID => 3, Distance => 2.3, RouteDistance => 4.3 },
						{ ID => 2, Distance => 1.5, RouteDistance => 2.8 },
						{ ID => 5, Distance => 2.1, RouteDistance => 0 },
						{ ID => 1, Distance => 1.7, RouteDistance => 2.5 });

my @sorted = sort { 
	if($a->{RouteDistance} == 0 || $b->{RouteDistance} == 0)
	{
		return ($a->{Distance} < $b->{Distance}) ? -1 : 1;
	}
	elsif ($a->{RouteDistance} == $b->{RouteDistance})
	{	
		return 0;
	}
	else
	{
		return ($a->{RouteDistance} < $b->{RouteDistance}) ? -1 : 1;
	}
} @unsorted_array;


foreach my $sorted_row (@sorted)
{
	print "ID: ".$sorted_row->{'ID'}." Distance: ".$sorted_row->{'Distance'}." RouteDistance: ".$sorted_row->{'RouteDistance'}."\n";
}