static void UseImplicit()
{
StreamReader stream = new StreamReader(new MemoryStream());
var text = new TextClass();
Shape shape = text;
text.Hieght = 200;
shape.Width = 100;
Console.WriteLine(text.Width);
}
static void UseExplicit()
{
Shape shape = new TextClass();
TextClass text = (TextClass)shape;
var x = shape as TextClass;
if (x != null)
{
Console.WriteLine("Up casting method!");
}
}