C#

Guffa wrote:

Why isn't the class abstract?

Guffa wrote:

You only have a use for the interface if you have a need to make a completely different implementation of the vehicle members for any class.

.method public hidebysig static class Vehicle CreateVehicle() cil managed
{
    .maxstack 8
    L_0000: newobj instance void Car::.ctor()
    L_0005: ret 
}

// C# code
public static Car ConvertToCar( Vehicle v )
{
    return (Car) v;
}
 
// IL code
 
.method public hidebysig static class Car ConvertToCar(class Vehicle v) cil managed
{
    .maxstack 8
    L_0000: ldarg.0 
    L_0001: castclass Car
    L_0006: ret 
}

// C# code
public static Car TryConvertToCar( Vehicle v )
{
    return v as Car;
}
 
public static bool IsCar( Vehicle v )
{
    return v is Car;
}
 
// IL code
.method public hidebysig static class Car TryConvertToCar(class Vehicle v) cil managed
{
    .maxstack 8
    L_0000: ldarg.0 
    L_0001: isinst Car
    L_0006: ret 
}
 
.method public hidebysig static bool IsCar(class Vehicle v) cil managed
{
    .maxstack 8
    L_0000: ldarg.0      // push v onto stack
    L_0001: isinst Car   // convert item on stack to a Car,
                         // or replace with null if it isn't one
    L_0006: ldnull       // push a null onto the stack
    L_0007: cgt.un       // Is the second item on the stack greater
                         // (unsigned) than the first? Replace top item
                         // with result
    L_0009: ret          // return top item on stack as result
}

public static bool IsCar( Vehicle v )
{
    Car c = v as Car;
    return c != null;
}

using (Bitmap b = new Bitmap(form1.Width, form1.Height)) {
   DrawToBitmap(b, new Rectangle(0, 0, form1.Width, form1.Height));
   b.Save(fileName, ImageFormat.Png);
}