What is object casting?

Question

I\'m a bit confused about what exactly object casting is and what it\'s used for. I\'ve read the MSDN documentation about Casting and type conversion, where I can see that f

Answer 1

A simple valid example goes back to older versions of C#. List didn't exist in that version and in order to store a collection of data you had to use a non-generic collection:

static void Main(string[] args)
{
   ArrayList list = new ArrayList();
   list.Add(1);
   list.Add(2);
   list.Add(3);

   int total = 0;
   foreach(object item in list)
      total += (int)item; // without casting, compiler never knows item is int

   Console.WriteLine("Total = {0}", total);
}

Another valid example is events, most events use the signature (object sender, EventArgs e). In order to access the elements of the sender, a button for example, then you need to cast:

Button btn = (Button)sender;
Console.WriteLine(btn.Text);

It is a better practice to use the as operator over the normal casting to prevent null reference exception, but the above is just to provide valid examples.