sub getNurls {
	my( $s, $n ) = @_;
	my @urls = split /,?(https?:\/\/)/, $s;
	return map { defined $urls[2*$_-1]?$urls[2*$_-1].$urls[2*$_]:() } (1..$n);
}

my $max = 2;
my $input = q|http://abc.org,http://de,f.org,https://ghi.org|;
print "$_\n" for getNurls( $input, $max );