Inline If problem

MarkB123

Can anyone explain why the following won't compile and a possible solution... string strSequence = (view.GetFocusedValue().ToString() == String.IsNullOrEmpty ? view.GetFocusedValue().ToString() : ""); I get the following error... Error 16 Operator '==' cannot be applied to operands of type 'string' and 'method group'. Many Thanks

Pete OHanlon

String.IsNullOrEmpty is a method, not a property. Try to use this instead:

string strSequence = (string.IsNullOrEmpty(view.GetFocusedValue().ToString()) ? view.GetFocusedValue().ToString() : string.Empty);

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Lost User

.IsNullOrEmpty is a method change to .Empty

OriginalGriff

stancrm wrote:

change to .Empty

Trust me, having if conditions that change variable contents is a good way to really mess your code up and cause such nasty bugs! I don't think Empty() does quite what you think it does...

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Lost User

Ok wait, what are you trying to achieve? This code (even if I pretend that the == works) does not do anything useful. Suppose view is null: NullReferenceException Or the value returned by GetFocusedValue is null: NullReferenceException Or the value returned by ToString is null: strSequence is null ToString returns "": strSequence is "" ToString returns anything else: strSequence is "" So you either get an exception, or you get a useless value in strSequence. What's the deal here? What did you want to do? If what you want is: the value of view.GetFocusedValue().ToString() if it isn't null, or "" if it is null Then you could do: string strSequence = view.GetFocusedValue().ToString() ?? ""; Disclaimer: I just woke up, it's entirely possible that I'm not making any sense at all - sorry!

Pete OHanlon

string.Empty doesn't change the value of the string unless you assign it, and the OP was doing an equality test. What do you think it does? If his test is if (value == string.Empty), this doesn't change value.

"WPF has many lovers. It's a veritable porn star!" - Josh Smith

As Braveheart once said, "You can take our freedom but you'll never take our Hobnobs!" - Martin Hughes.

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Lost User

ms fxcop says: dont use : (value == string.Empty) use: (value.Length == 0)

MarkB123

Perfect - Many Thanks.

Pete OHanlon

Indeed, but that's for a separate issue (i.e. it's quicker to check the length). The fuller check is to use string.IsNullOrEmpty to check because the value might be null or it might be empty, in which case value.Length would throw an ArgumentNullException.

"WPF has many lovers. It's a veritable porn star!" - Josh Smith

As Braveheart once said, "You can take our freedom but you'll never take our Hobnobs!" - Martin Hughes.

My blog | My articles | MoXAML PowerToys | Onyx

MarkB123

Harold, Thanks for that - I think that is exactly what I need. Basically all I want to do is check if View.GetFocusedValue... is null. If it is null then assign a "" otherwise use the View.GetFocusedValue. What will happen with it if the value comming back happens to be DBNull.Value (assuming I was doing something with a dataset. Thanks

Lost User

With the code I suggested you could still get a nasty NullRef, but how about

var FocusVal = view.GetFocusedValue();
string strSequence = "";
if (FocusVal != null)
strSequence = FocusVal.ToString();

Alternatively:

string strSequence = (view.GetFocusedValue() != null) ? view.GetFocusedValue().ToString() : "";

Would call GetFocusedValue twice though so only use if that's ok. Or if GetFocusedValue returns a string:

string strSequence = view.GetFocusValue() ?? "";

edit: oh I missed the DBNull thing, well that might change things in ways unknown to me - I've never used database code.. :(

OriginalGriff

Pete O'Hanlon wrote:

string.Empty doesn't change the value of the string unless you assign

You are absolutely right, and I grovel, lots. :-O I can only blame complete and utter brain failure, brought on by unexpected sunshine.

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