What is the minimum interface that has the Count property in .Net

Question

I need to change a method that has one parameter that takes a serie of objects. I need to find the lowest Interface (in inheritance tree) that has the Count property. Until now I was using the IEnumerable but as this has not Count I need to change it to the wider interface possible so the method can work with the biggest number of types of series (collections, lists, arrays, etc).

Thanks in advance.

Answer 1

ICollection adds the Count property.

As @Joren rightly points point, IEnumerable<T> has the extension method Count<T>() if you're happy making your collection generic. However, as @Joel Coehoorn has pointed out, it is inadvisable to use this as it forces an iteration of the sequence.

Answer 2

ICollection adds the Count property.

Answer 3

System.Collections.ICollection, and also System.Collections.Generic.ICollection<T>. These two interfaces have no relation to eachother, but both inherit from IEnumerable, so they're at the same level.

IEnumerable obviously does not have a Count property (the count isn't necessarily predetermined).