can someone explain me the difference between IList and List ?

Question

Sam Hobbs · Answer

The difference is easy to understand when you understand interfaces. C# has very many interfaces. You cannot create (get memory for) an instance of an interface; in other words you cannot do either of the following: IList thelist = new IList (); IList thelist = new IList(); C# (actually .Net) uses IList when a class or struct that derives from IList can be used. In other words as a beginner you normally cannot use IList . When .Net uses IList you will usually use List .

Abhishek Yadav · Answer

In C# the `List` class is a generic class that is part of the `System.Collections.Generic` namespace while the `IList` interface is a non-generic interface that is part of the `System.Collections` namespace. Here are some key differences between `List` and `IList` in C#: 1. Type safety: `List` is a strongly typed generic collection class which means that it can only store elements of a specific type. On the other hand `IList` is not type-safe and can store elements of any type. 2. Methods: `List` class includes additional methods such as `AddRange` `InsertRange` `RemoveRange` `Sort` etc. which are not available in the `IList` interface. 3. Performance: `List` is generally more performant than `IList` because it is a concrete class while `IList` is an interface that can be implemented in different ways. 4. Inheritance: `List` is a concrete class while `IList` is an interface. This means that a class can inherit from `List` but it can only implement `IList`. Overall `List` is the preferred choice for most scenarios due to its type safety additional methods and better performance compared to `IList`.

Tuhin Paul · Answer

For example the List class in C# implements the IList interface. So instead of directly instantiating an IList you would typically use List : List thelist = new List ();

Tuhin Paul · Answer

Instead of IList use a more relatable interface like IShape. Show how a class like Circle or Square can implement IShape and provide its specific implementation details. You could mention other common interfaces like IComparable or IEnumerable and how they are used in collections.

Jayraj Chhaya · Answer

List and IList are related but have distinct differences. List is a class that implements IList  which is an interface. List provides more functionality and is mutable allowing you to add remove and modify elements. On the other hand IList is an interface that defines properties and methods for collections. Where to Use: List : Use List when you need a dynamic array that can grow or shrink in size. IList : Use IList when you want to work with collections in a more generic way without specifying a particular implementation. Real-Life Example: Imagine you have a shopping cart. You would use a List to store the items because you need to add remove or update items dynamically. However if you have a method that accepts any collection type you would use IList as a parameter type. In summary List is mutable and provides more features while IList is more generic and allows flexibility in working with different collection types.