Should I use IEnumerable or ICollection?

Should I use IEnumerable or ICollection?

IEnumerable contains only GetEnumerator() method, like read-only iterate. ICollection is one step ahead of IEnumerable. If we want some more functionality like Add or remove element, then it is better to go with ICollection because we cannot achieve that with IEnumerable. ICollection extends IEnumerable.

What is the difference between ICollection and IEnumerable?

An IEnumerable is a list or a container which can hold some items. You can iterate through each element in the IEnumerable. ICollection is another type of collection, which derives from IEnumerable and extends it’s functionality to add, remove, update element in the list.

Which is better IList or list?

The main difference between List and IList in C# is that List is a class that represents a list of objects which can be accessed by index while IList is an interface that represents a collection of objects which can be accessed by index. Overall, List is a concrete type that implements the IList interface.

What is the use of IEnumerable ICollection IList and IDictionary?

To begin with, all the interfaces (ICollection, IList, IQueryable, IDictionary) inherit from IEnumerable, which allows us to use the foreach statement. ICollection: is the most basic interface among these, it is enumerable and it supports Count operator. IQueryable: an enumerable interface that supports LINQ.

Is IEnumerable faster than list?

So it isn’t that IEnumerable is more efficient than list in a “performance” or “runtime” aspect. It’s that IEnumerable is a more efficient design construct because it’s a more specific indication of what your design requires. (Though this can lead to runtime gains in specific cases.)

Why do we use IEnumerable?

IEnumerable interface is used when we want to iterate among our classes using a foreach loop. The IEnumerable interface has one method, GetEnumerator, that returns an IEnumerator interface that helps us to iterate among the class using the foreach loop.

Why is multiple enumeration bad?

Summary. Enumerating a sequence twice can multiply the cost of an entire path through your program by two. When it happens several times on the same path, the slowdown compounds and becomes unmanageable. Prefer caching during the first enumeration over re-enumerating.

Is IEnumerable in memory?

Key findings. IEnumerable is read-only and List is not. List implements IEnumerable, but represents the entire collection in memory. LINQ expressions return an enumeration, and by default the expression executes when you iterate through it using a foreach, but you can force it to iterate sooner using .

When should I return IEnumerable?

To be less colloquial, you can return IEnumerable when you want to make it clear to consumers of your method that they cannot modify the original source of information. It’s important to understand that if you’re going to advertise this, you should probably exercise care in how the thing you’re returning will behave.

How do I return an IList?

Returning IList<IList> I’d like to have the return type use the generic IList<> interface to reduce coupling with the concrete List<> type downstream.

What is the return type of IEnumerable?

IEnumerable has just one method called GetEnumerator. This method returns another type which is an interface that interface is IEnumerator. If we want to implement enumerator logic in any collection class, it needs to implement IEnumerable interface (either generic or non-generic).

What does IEnumerable mean?

IEnumerable is an interface defining a single method GetEnumerator() that returns an IEnumerator interface. It is the base interface for all non-generic collections that can be enumerated. This works for read-only access to a collection that implements that IEnumerable can be used with a foreach statement.

What is IEnumerator C#?

IEnumerable is an interface defining a single method GetEnumerator() that returns an IEnumerator interface. This works for readonly access to a collection that implements that IEnumerable can be used with a foreach statement. IEnumerator has two methods MoveNext and Reset. It also has a property called Current.

What is difference between IEnumerable and IQueryable in C#?

Querying data from a database, IEnumerable execute a select query on the server side, load data in-memory on a client-side and then filter data. Querying data from a database, IQueryable execute the select query on the server side with all filters. IEnumerable Extension methods take functional objects.

Where is IQueryable used?

IQueryable uses Expression objects that result in the query being executed only when the application requests an enumeration. Use IQueryable when you have to run ad-hoc queries against data source like LinQ to SQL Server,Entity framework and other sources which implement IQueryable.

What is IQueryable?

The IQueryable interface inherits the IEnumerable interface so that if it represents a query, the results of that query can be enumerated. Enumeration causes the expression tree associated with an IQueryable object to be executed. The definition of “executing an expression tree” is specific to a query provider.

What is IQueryable return?

By returning IQueryable you automatically tie your repository layer to any data persistence technology that properly implements IQueryable .

How do you count in IQueryable?

  1. Can’t you just convert the returned IQueryable to a list and take the count? < code> .ToList().count should give you the count. – Ram Iyer Jan 21 ’15 at 10:49.
  2. Upvote for you Ram Iyer. Thanks. – Cameron T Nov 22 ’19 at 18:04.

How do you use count in lambda expression?

The first overload method of Count returns the number of elements in the specified collection, whereas the second overload method returns the number of elements which have satisfied the specified condition given as lambda expression/predicate function. The following example demonstrates Count() on primitive collection.

How do I use count in Entity Framework?

SELECT COUNT(*) FROM [MyTable] WHERE [fkID] = ‘1’; I could load all of the rows and then find the Count with: var owner = context.

Why IEnumerable does not support lazy loading?

IQueryable supports deferred execution. IEnumerable doesn’t support lazy loading. IQueryable support lazy loading. Hence it is suitable for paging like scenarios.

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