Short and null

Question

HI!! Let say I have an object and this object has a property of the type short. How I can check if someone set this property? When i try to check this like that: if( myObject.MyShortProperty != null ) { } I get an null reference exception. How I can check this without a null references exception? regards, gicio

shimtanny · Answer

Yep, you're right... thanks.

sacresp · Answer

No Simon, that won't cause "object not set on an instance" exception. The problems is that myObject is a null here :) But Simon is right about shorts not having null values. gicio, you need to add check if (myObject != null && myObject.myShortProperty != 0) short.minValue is often used as a replacement to nulls. So initialize your members to short.MinValue, so you can check whether it has changed from that. 0 can be a real value in many cases, minValue is much more rare.

mibuyt · Answer

Hi, Maybe you can look at PropertyInfo.GetAccessors Method Returns an array whose elements reflect the public get, set, and other accessors of the property reflected by the current instance. Keep me updated. Cheers.

shimtanny · Answer

Hi The problem is, that short (System.Int16) is not a reference type. Short is a value type and null is not a valid value for it. If you wannt to differ between 0 and something else set, use the following: if (myObject.MyShortPrpoerty != 0) { // do something... } If you wannt just check if anyone has changed the property value, create a helper member, for instance HasChanged, as property or method. Manage internally a bool value for instance called "private bool hasChanged = false;" Simon