Quick Interface Question...

[z_learning_tester]

//Let's say the Document class implements the IStorable interface...

class Document : IStorable
{...}

//Then we create a document object...
Document doc = new Document();

//Then we have the following line of code(the part I don't understand)...
IStorable isDoc = doc as Istorable;

Is this last line the same as saying:
IStorable isDoc = (IStorable) doc;

In other words, is the "as" word, just another way of casting?
Thanks,

Jeff

[Steven Behnke]

Yes, as casts, but rather than throwing an InvalidCastException if it
cannot property type cast from one type to another it sets the reference
to null. So you should always check that the resulting object is not
null before trying to work with it or you will receive a
NullReferenceException.

Thanks,
Steven

z_learning_tester wrote:

//Let's say the Document class implements the IStorable interface...

class Document : IStorable
{...}

//Then we create a document object...
Document doc = new Document();

//Then we have the following line of code(the part I don't understand)...
IStorable isDoc = doc as Istorable;

Is this last line the same as saying:
IStorable isDoc = (IStorable) doc;

In other words, is the "as" word, just another way of casting?
Thanks,

Jeff

[Jon Skeet [C# MVP]]

z_learning_tester <so*****@microsoft.com> wrote:

In other words, is the "as" word, just another way of casting?

See http://www.pobox.com/~skeet/csharp/faq#cast.as

--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet
If replying to the group, please do not mail me too

[z_learning_tester]

Oh, so that explains the if(Istorable != Null)... that followed ;-)
If the 'as' check for a valid cast failed, it would return null...
Thanks!

Jeff

"Steven Behnke" <st****@xsdev.net> wrote in message
news:dVMDc.961$876.426@fed1read07...

Yes, as casts, but rather than throwing an InvalidCastException if it
cannot property type cast from one type to another it sets the reference
to null. So you should always check that the resulting object is not
null before trying to work with it or you will receive a
NullReferenceException.

Thanks,
Steven

z_learning_tester wrote:

//Let's say the Document class implements the IStorable interface...

class Document : IStorable
{...}

//Then we create a document object...
Document doc = new Document();

//Then we have the following line of code(the part I don't understand)... IStorable isDoc = doc as Istorable;

Is this last line the same as saying:
IStorable isDoc = (IStorable) doc;

In other words, is the "as" word, just another way of casting?
Thanks,

Jeff

[z_learning_tester]

Thanks for the reference.
I wish C# would last a little longer.
Now I'm afraid that by the time I learn it, Whidbey will be out and I'll
have to start over.
Oh well, that's technology...
Thanks again!

Jeff
"Jon Skeet [C# MVP]" <sk***@pobox.com> wrote in message
news:MP************************@msnews.microsoft.c om...

z_learning_tester <so*****@microsoft.com> wrote:

In other words, is the "as" word, just another way of casting?

See http://www.pobox.com/~skeet/csharp/faq#cast.as

--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet
If replying to the group, please do not mail me too

[Jon Skeet [C# MVP]]

z_learning_tester <so*****@microsoft.com> wrote:

Thanks for the reference.
I wish C# would last a little longer.
Now I'm afraid that by the time I learn it, Whidbey will be out and I'll
have to start over.
Oh well, that's technology...

You certainly won't have to start over. C# v2.0 will have things added,
but I don't think much (if anything) will be taken away. Sure, you may
never need to use ArrayList.ToArray(Type) again, but most of what
you're learning now will still be useful.

--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet
If replying to the group, please do not mail me too