List <T> Order

Question

I have a problem, I allow the user to select the criteria for ordering a list

Let's say my list is called

List<Cars> AllCars = new List<Cars>;
allCars = //call the database and get all the cars

Now I want to order this list

allCars.orderBy(registrationDate)

I understand that this does not work, but I do not have anyidea that I should put in brackets.

Answer 1

allCars.OrderBy(c => c.RegistrationDate);

Answer 2

I understand that this does not work, but I do not have anyidea that I should put in brackets.

Announcement Enumerable.OrderBy-

public static IOrderedEnumerable<TSource> OrderBy<TSource, TKey>(
    this IEnumerable<TSource> source,
    Func<TSource, TKey> keySelector
)

and since this is an extension method, it can be called as

source.OrderBy(keySelector).

Yours List<Car>plays a role sourcelike List<T> : IEnumerable<T>. The second parameter is more interesting and one that you confuse. It is declared as type

Func<TSource, TKey>

, , TSource ( Car) TKey; , TKey. , Car.registrationDate, TKey is DateTime. , ?

DateTime GetRegistrationDate(Car car) {
    return car.registrationDate;
}

OrderBy :

allCars.OrderBy(GetRegistrationDate).

# 2.0 ; , .

allCars.OrderBy(delegate(Car car) { return car.registrationDate; });

# 3.0 -,

allCars.OrderBy(car => car.registrationDate);

c => c.registrationDate - -, Func<Car, DateTime>, Enumerable.OrderBy.

allCars.orderBy(registrationDate)

, registrationDate . , - registrationDate . , Car.registrationDate , , ConferenceAttendee.registrationDate . , Car.registrationDate. , .