Problem with sorting objects - linq

Question

I have a collection of Car:
var cars = new List<Car>();
cars.Add(new Car { ProductionDate = new DateTime(2011,02,02) });
cars.Add(new Car { ProductionDate = new DateTime(2011, 01, 01) });
cars.Add(new Car { ProductionDate = new DateTime(2011,04,04,04,04,04) });
cars.Add(new Car { ProductionDate = new DateTime(2011, 03, 03, 3, 3, 3) });
I need to sort it by ProductionDate.
Result should be that at first I will have cars with date with time, so it should be car with 2011, 03, 03, 3, 3, 3 as production date, and at the end should be car with 2011, 02, 02 as production date. Second should be car with 2011, 04, 04, 04, 04, 04, and the third with 2011, 02, 02.
I can do it by using foreach but I believe that there is nicer way to do it.

Answer 1

cars.Sort((p, q) => {
var tm1 = p.ProductionDate.TimeOfDay;
var tm2 = q.ProductionDate.TimeOfDay;
if (tm1.Ticks == 0) {
if (tm2.Ticks == 0) {
return p.ProductionDate.CompareTo(q.ProductionDate);
}
return 1;
} else if (tm2.Ticks == 0) {
return -1;
} else {
return p.ProductionDate.CompareTo(q.ProductionDate);
}
});
But remember: what happens if a car is built at 0:00? A DateTime is made of a Data+Time. You can't see if the Time part is missing!
I'll add that if you need to use the Enumerable.OrderBy, then you can use my lamdba function with the LambdaComparer that you can find around the internet (as suggested by sll)

Answer 2

TimeSpan zeroTime = new TimeSpan(0);
var sortedCars = cars.OrderBy(c => c.ProductionDate.TimeOfDay.Equals(zeroTime) ? 1 : 0)
.ThenBy(c => c.ProductionDate)
.ToList();

Answer 3

I have something like that
var carsWithoutProductionTime = from car in cars
where car.ProductionDate.Hour == 0
orderby car.ProductionDate
select car;
var carsWithProductionTime = from car in cars
where car.ProductionDate.Hour != 0
orderby car.ProductionDate
select car;
var mergedCars = carsWithProductionTime.Union(carsWithoutProductionTime);
but It looks ugly. I would like to see something more sophisticated :)