int[] arr = new int[5];
Console.WriteLine(arr.Count.ToString());//Compiler Error
Console.WriteLine(((ICollection)arr).Count.ToString());//works print 5
Console.WriteLine(arr.Length.ToString());//print 5
Do you have an explanation for that?
Arrays have .Length, not .Count.
But this is available (as an explicit interface implementation) on ICollection etc.
Essentially, the same as:
interface IFoo
{
int Foo { get; }
}
class Bar : IFoo
{
public int Value { get { return 12; } }
int IFoo.Foo { get { return Value; } } // explicit interface implementation
}
Bar
doesn't have public a Foo
property - but it is available if you cast to IFoo
:
Bar bar = new Bar();
Console.WriteLine(bar.Value); // but no Foo
IFoo foo = bar;
Console.WriteLine(foo.Foo); // but no Value
While System.Array
implement the ICollection
interface it doesn't directly expose the Count
property. You can see the explicit implementation of ICollection.Count
in the MSDN documentation here.
The same applies to IList.Item
.
Take look at this Blog entry for more details on explicit and implicit interface implementation: Implicit and Explicit Interface Implementations
Whilst this doesn't answer your question directly, if you are using .NET 3.5 you can include the namespace;
using System.Linq;
which will then allow you to use a Count() method, similar to when casting your int array as an ICollection.
using System.Linq;
int[] arr = new int[5];
int int_count = arr.Count();
You also then have a whole host of nice functions you can use in Linq too :)