Chapter 14 Exercise 4

ich · May 24th, 2012, 03:42 AM

Can anyone tell me the difference between these two lines of code:

Code:

Picture myPicture = e.Entity as Picture;

and

Code:

Picture myPicture = (Picture)e.Entity;

The first is the answer code give for this exercise, the second is the code given earlier in the chapter for the EntityDataSOurce_Inserting event.

Thanks.

Imar · May 24th, 2012, 08:19 AM

Hi there,

Both do more or less the same thing: they cast e.Entity to a Picture type.

The difference is that the "as" operator does not throw an exception but simply returns null in ase e.Entity is null or not a Picture. Casting using (Picture) does crash when the value you try to cast is null or not a Picture.

Both code example can be interchanged in these examples as e.Entity should contain a valid Picture.

For more details see page 146.

Cheers,

Imar