我无法访问数组的Count属性，但通过强制转换为ICollection！

        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
        int[] arr = new int[5];
        Console