Null value in vb.net 2008

Just tried it. No runtime errors for type mismatching, but the function call fails, the existing value doesn't get overwritten. Is this an error message? There's no error message, but there's also no effect. The goal is to overwrite an existing registry value with nothing. A null string like "". The problem is that it's not just a string, it's an array of strings. Visual Basic, however, takes care of adding the final terminating null when we pass the string by value".

Proposed as answer by konikula Wednesday, November 12, AM. Object , ByVal e As System. EventArgs Handles MyBase. Wednesday, November 12, AM. Could System. IntPtr to Array differ from direct calling api with Array as argument? Proposed as answer by konikula Wednesday, November 12, PM. I am using Visual Studio with Visual Basic. NET I am trying to set it to NULL. John Anthony Oliver I tried doing this with just a one element array since I don't need 10 elements, or any elements really, just all NULL but that didn't work.

NullChar That is what I tried. I get a type mismatch error. Stephen J Whiteley. SJWhiteley said: If that's the case, then you should look at the System. I very well might have to do that, but I was really hoping that VB. NET had the functionality I wanted. Consider a database that tracks work-related activities.

The following example constructs a nullable Boolean type and declares a variable of that type. You can write the declaration in three ways:. Its initial default value is no value at all, which in this case could mean that the information has not yet been obtained for this person. In contrast, False could mean that the information has been obtained and the person does not ride the bus to work. You can declare variables and properties with nullable value types, and you can declare an array with elements of a nullable value type.

You can declare procedures with nullable value types as parameters, and you can return a nullable value type from a Function procedure. You cannot construct a nullable type on a reference type such as an array, a String , or a class.

The underlying type must be a value type. For more information, see Value Types and Reference Types. The most important members of a nullable value type are its HasValue and Value properties. For a variable of a nullable value type, HasValue tells you whether the variable contains a defined value.

If HasValue is True , you can read the value from Value. When you declare a variable with a nullable value type, its HasValue property has a default value of False. This means that by default the variable has no defined value, instead of the default value of its underlying value type. For comparison, the alternative code for the first of these expressions without a null-conditional operator is:.

Sometimes you need to take an action on an object that may be null, based on the value of a Boolean member on that object like the Boolean property IsAllowedFreeShipping in the following example :.

You can shorten your code and avoid manually checking for null by using the null-conditional operator as follows:. The null-conditional operators are short-circuiting. Another use for null-conditional member access is to invoke delegates in a thread-safe way with much less code. The following example defines two types, a NewsBroadcaster and a NewsReceiver.

See if this solution works for you by signing up for a 7 day free trial. What do I get with a subscription? With your subscription - you'll gain access to our exclusive IT community of thousands of IT pros.

We can't always guarantee that the perfect solution to your specific problem will be waiting for you. If you ask your own question - our Certified Experts will team up with you to help you get the answers you need. Who are the certified experts? How quickly will I get my solution? We can't guarantee quick solutions - Experts Exchange isn't a help desk.