c# Casting v As operator
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For those using c#, what do you prefer? A.
SomeObject obj = (SomeObject) e;
or B.
SomeObject obj = e as SomeObject;
www.software-kinetics.co.uk Wear a hard hat it's under construction
It depends on the situation. Normally, I prefer to cast with the
asoperator because I don't have to catch the exception, and it just feels more natural for me to not have code like this:MyClass c = null;
try
{
c = (MyClass)variable;
}
catch(InvalidCastException)
{
c = new MyClass();
}Of course, there are times where you can't use
as, so in those cases you use the()casting form.Forgive your enemies - it messes with their heads
My blog | My articles | MoXAML PowerToys | Mole 2010 - debugging made easier - my favourite utility
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It depends. (A) will throw if the cast fails while (B) will evaluate to
nullif the cast fails. I use both depending on how I intend to handle the casting failure. /raviMy new year resolution: 2048 x 1536 Home | Articles | My .NET bits | Freeware ravib(at)ravib(dot)com
Correct answer.
".45 ACP - because shooting twice is just silly" - JSOP, 2010
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You can never have too much ammo - unless you're swimming, or on fire. - JSOP, 2010
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"Why don't you tie a kerosene-soaked rag around your ankles so the ants won't climb up and eat your candy ass." - Dale Earnhardt, 1997 -
I prefer
asbecause it is safer:expression as type
is equivalent to:
expression is type ? (type)expression : (type)null
When you use casting you can get
StoopidTypeException.
Panic, Chaos, Destruction. My work here is done. Drink. Get drunk. Fall over - P O'H OK, I will win to day or my name isn't Ethel Crudacre! - DD Ethel Crudacre I cannot live by bread alone. Bacon and ketchup are needed as well. - Trollslayer Have a bit more patience with newbies. Of course some of them act dumb - they're often *students*, for heaven's sake - Terry Pratchett
I did not know this. I'm currently working on stuff with a common base interface with multipe derived interfaces and I've been playing about with GetType and typeof to try to get the correct derived interface from a base interface. So reading lounge posts may have been productive today. :-D
Pete
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No, because the two are not equivalent (see other posts below).
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Hardly :|
www.software-kinetics.co.uk Wear a hard hat it's under construction
If a noob had asked that question in the Lounge they'd have been toast.
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For those using c#, what do you prefer? A.
SomeObject obj = (SomeObject) e;
or B.
SomeObject obj = e as SomeObject;
www.software-kinetics.co.uk Wear a hard hat it's under construction
B. Because apart from what others have mentioned in favor of b, it will automagically do a QueryInterface as well in case of a COM interface call.
A year spent in artificial intelligence is enough to make one believe in God
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True, but you should know beforehand if the casting is correct.
www.software-kinetics.co.uk Wear a hard hat it's under construction
Norm .net wrote:
True, but you should know beforehand if the casting is correct.
"Should" is a dangerous word. :) A plugin discovery mechanism (that makes extensive use of reflection) I recently built assumes nothing regarding the type of object that was loaded. /ravi
My new year resolution: 2048 x 1536 Home | Articles | My .NET bits | Freeware ravib(at)ravib(dot)com
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Sorry - wrong. The answer's a, because it's better.
"The difference between genius and stupidity is that genius has its limits." - Albert Einstein
"As far as we know, our computer has never had an undetected error." - Weisert
"If you are searching for perfection in others, then you seek disappointment. If you are seek perfection in yourself, then you will find failure." - Balboos HaGadol Mar 2010
There seems to be alot of white space in your sig.
Panic, Chaos, Destruction. My work here is done. Drink. Get drunk. Fall over - P O'H OK, I will win to day or my name isn't Ethel Crudacre! - DD Ethel Crudacre I cannot live by bread alone. Bacon and ketchup are needed as well. - Trollslayer Have a bit more patience with newbies. Of course some of them act dumb - they're often *students*, for heaven's sake - Terry Pratchett
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If a noob had asked that question in the Lounge they'd have been toast.
It's a debate, not a question.
www.software-kinetics.co.uk Wear a hard hat it's under construction
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B. Because apart from what others have mentioned in favor of b, it will automagically do a QueryInterface as well in case of a COM interface call.
A year spent in artificial intelligence is enough to make one believe in God
Good point, I suppose not many noobies would know about QueryInterface, ah those were the days. :)
www.software-kinetics.co.uk Wear a hard hat it's under construction
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For those using c#, what do you prefer? A.
SomeObject obj = (SomeObject) e;
or B.
SomeObject obj = e as SomeObject;
www.software-kinetics.co.uk Wear a hard hat it's under construction
If an illegal cast is an exceptional (woah, that should never happen) situation, then (a) If there's a possibility that through normal use the cast might be invalid (e.g. Plug-in tpye code), then (b), followed by an If to check for Null. -Richard
Hit any user to continue.
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Good point, I suppose not many noobies would know about QueryInterface, ah those were the days. :)
www.software-kinetics.co.uk Wear a hard hat it's under construction
Yeah... I always ended up using CComPtr to avoid reference-leak issues. MS should have banned direct use of QueryInterface and CoCreateInstance anyway. RAII should have been the way from onset.
A year spent in artificial intelligence is enough to make one believe in God
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Yeah... I always ended up using CComPtr to avoid reference-leak issues. MS should have banned direct use of QueryInterface and CoCreateInstance anyway. RAII should have been the way from onset.
A year spent in artificial intelligence is enough to make one believe in God
I used raw COM when the COM specs where first released, wow you needed a ton of code to do a small task. But it did give me background on the workings of COM.
www.software-kinetics.co.uk Wear a hard hat it's under construction
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If an illegal cast is an exceptional (woah, that should never happen) situation, then (a) If there's a possibility that through normal use the cast might be invalid (e.g. Plug-in tpye code), then (b), followed by an If to check for Null. -Richard
Hit any user to continue.
Richard A. Dalton wrote:
Plug-in tpye code
That's the only situation I could eve think off, normally you should be aware if the cast would fail or not.
www.software-kinetics.co.uk Wear a hard hat it's under construction
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I used raw COM when the COM specs where first released, wow you needed a ton of code to do a small task. But it did give me background on the workings of COM.
www.software-kinetics.co.uk Wear a hard hat it's under construction
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For those using c#, what do you prefer? A.
SomeObject obj = (SomeObject) e;
or B.
SomeObject obj = e as SomeObject;
www.software-kinetics.co.uk Wear a hard hat it's under construction
It depends on what you're trying to do, the two things are different. If you're certain e is a SomeObject then I'd cast it. If it may or may not be I'd usually use the as keyword, in which case obj would be null if it isn't a SomeObject as opposed to throwing an exception.
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There seems to be alot of white space in your sig.
Panic, Chaos, Destruction. My work here is done. Drink. Get drunk. Fall over - P O'H OK, I will win to day or my name isn't Ethel Crudacre! - DD Ethel Crudacre I cannot live by bread alone. Bacon and ketchup are needed as well. - Trollslayer Have a bit more patience with newbies. Of course some of them act dumb - they're often *students*, for heaven's sake - Terry Pratchett
Possibly a font-problem on your end? It looks roughly like: W**.'.** Balboos - the three punctuation-like characters being the HTML character code:
& there4;(space put in after & so it doesn't render)"The difference between genius and stupidity is that genius has its limits." - Albert Einstein
"As far as we know, our computer has never had an undetected error." - Weisert
"If you are searching for perfection in others, then you seek disappointment. If you are seek perfection in yourself, then you will find failure." - Balboos HaGadol Mar 2010
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Oh that brings back memories, and forgetting idl files :)
www.software-kinetics.co.uk Wear a hard hat it's under construction
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Possibly a font-problem on your end? It looks roughly like: W**.'.** Balboos - the three punctuation-like characters being the HTML character code:
& there4;(space put in after & so it doesn't render)"The difference between genius and stupidity is that genius has its limits." - Albert Einstein
"As far as we know, our computer has never had an undetected error." - Weisert
"If you are searching for perfection in others, then you seek disappointment. If you are seek perfection in yourself, then you will find failure." - Balboos HaGadol Mar 2010
Not your name, your sig:
W∴ Balboos wrote:
Possibly a font-problem on your end?
It looks roughly like: W**.'.** Balboos - the three punctuation-like characters being the HTML character code:& there4;(space put in after & so it doesn't render)"The difference between genius and stupidity is that genius has its limits." - Albert Einstein
"As far as we know, our computer has never had an undetected error." - Weisert
"If you are searching for perfection in others, then you seek disappointment. If you are seek perfection in yourself, then you will find failure." - Balboos HaGadol Mar 2010
There's a lot of white space...
Panic, Chaos, Destruction. My work here is done. Drink. Get drunk. Fall over - P O'H OK, I will win to day or my name isn't Ethel Crudacre! - DD Ethel Crudacre I cannot live by bread alone. Bacon and ketchup are needed as well. - Trollslayer Have a bit more patience with newbies. Of course some of them act dumb - they're often *students*, for heaven's sake - Terry Pratchett
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It's a debate, not a question.
www.software-kinetics.co.uk Wear a hard hat it's under construction
To be or not to be.? That is a question. :-D
Panic, Chaos, Destruction. My work here is done. Drink. Get drunk. Fall over - P O'H OK, I will win to day or my name isn't Ethel Crudacre! - DD Ethel Crudacre I cannot live by bread alone. Bacon and ketchup are needed as well. - Trollslayer Have a bit more patience with newbies. Of course some of them act dumb - they're often *students*, for heaven's sake - Terry Pratchett
