From your code, it looks like provider is a variant or some other variable, and not an object. Is Nothing is for objects only, yet later you say it’s a value that should either be NULL or NOT NULL, which would be handled by IsNull. Try using: If Not IsNull(provider) Then url = url & … Read more
The If Not var1 Is Nothing Then Is a hangover from VB6. There didn’t used to be an IsNot, and so this was the only way to determine if a variable was not Nothing. It seems to be redundant in VB.NET.
This is one of the biggest sources of confusion with VB.Net, IMO. Nothing in VB.Net is the equivalent of default(T) in C#: the default value for the given type. For value types, this is essentially the equivalent of ‘zero’: 0 for Integer, False for Boolean, DateTime.MinValue for DateTime, … For reference types, it is the … Read more
If you take a look at the MSIL as it’s being executed you’ll see that it doesn’t compile down to the exact same code. When you use IsNothing() it actually makes a call to that method as opposed to just evaluating the expression. The reason I would tend to lean towards using “Is Nothing” is … Read more