Count property vs Count() method?

Question

Working with a collection I have the two ways of getting the count of objects; Count (the property) and Count() (the method). Does anyone know what

Answer 1

Decompiling the source for the Count() extension method reveals that it tests whether the object is an ICollection (generic or otherwise) and if so simply returns the underlying Count property:

So, if your code accesses Count instead of calling Count(), you can bypass the type checking - a theoretical performance benefit but I doubt it would be a noticeable one!

// System.Linq.Enumerable
public static int Count(this IEnumerable source)
{
    checked
    {
        if (source == null)
        {
            throw Error.ArgumentNull("source");
        }
        ICollection collection = source as ICollection;
        if (collection != null)
        {
            return collection.Count;
        }
        ICollection collection2 = source as ICollection;
        if (collection2 != null)
        {
            return collection2.Count;
        }
        int num = 0;
        using (IEnumerator enumerator = source.GetEnumerator())
        {
            while (enumerator.MoveNext())
            {
                num++;
            }
        }
        return num;
    }
}