C# get typeof null object

Asked 5 years, 5 months ago. Active 5 years, 5 months ago. Viewed 5k times. So I tried checking with a nullable bool: Console. Write typeof bool? Write a. Boolean bool? Write b. The exception that occured: An unhandled exception of type 'System. NullReferenceException' occurred in BoolTest. Improve this question. Community Bot 1 1 1 silver badge. Daniel Daniel 9, 12 12 gold badges 37 37 silver badges 74 74 bronze badges. NET and there are many oddities involving them, all of which have been beaten to death on SO.

You can search about it. Another one is, even though b. GetType fails, b. ToString doesn't. It has a reason in. NET but odd choice still. Another one is, had b been bool? GetType gives System. Boolean and not System. Add a comment. If so then it is similar to the case of a division by zero in Mathematics where the result is undefined. Not necessarily what you are looking for, though there is the question of how does one interpret null?

Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. NET : How do you get the Type of a null object? Ask Question. Asked 13 years, 2 months ago. Active 12 months ago. Viewed 24k times. I have a method with an out parameter that tries to do a type conversion.

ChangeType paramVal, destination. GetType destination is null, so we can't call. GetType on it. We also can not call: typeof destination because destination is a variable name not a type name. In practice, you don't know the lparam of the "equals", so I went with: string val; GetParameterValue "parameterName", out val ; And figured within the method, I would know the destination type of the output variable.

To partially solve my own problem, I can do: MyObj. GetField "SomeProp". Improve this question. Add a comment. Active Oldest Votes. Improve this answer. Marcus Griep Marcus Griep 7, 1 1 gold badge 22 22 silver badges 24 24 bronze badges. Good suggestion! Second argument should be typeof T and not typeof T.

I'll research this option a bit more It's possible if you don't mind declaring your method as a generic. Try this. Damian Powell Damian Powell 8, 6 6 gold badges 47 47 silver badges 58 58 bronze badges. Feedback will be sent to Microsoft: By pressing the submit button, your feedback will be used to improve Microsoft products and services. Privacy policy. A nullable value type T? For example, you can assign any of the following three values to a bool?

An underlying value type T cannot be a nullable value type itself. For more information, see Nullable reference types. The nullable value types are available beginning with C 2. Any nullable value type is an instance of the generic System. You typically use a nullable value type when you need to represent the undefined value of an underlying value type. For example, a Boolean, or bool , variable can only be either true or false.

However, in some applications a variable value can be undefined or missing. For example, a database field may contain true or false , or it may contain no value at all, that is, NULL.

You can use the bool? As a value type is implicitly convertible to the corresponding nullable value type, you can assign a value to a variable of a nullable value type as you would do that for its underlying value type.

You can also assign the null value. For example:. A boxing or unboxing conversion exists from the run-time type of an expression result to type T. The following example demonstrates that the is operator returns true if the run-time type of an expression result derives from a given type, that is, there exists a reference conversion between types:. The next example shows that the is operator takes into account boxing and unboxing conversions but doesn't consider numeric conversions :.

For information about C conversions, see the Conversions chapter of the C language specification. The following example shows how to use a declaration pattern to check the run-time type of an expression:. For information about the supported patterns, see Patterns. The as operator explicitly converts the result of an expression to a given reference or nullable value type. If the conversion isn't possible, the as operator returns null.

Unlike a cast expression , the as operator never throws an exception. The as operator considers only reference, nullable, boxing, and unboxing conversions. You can't use the as operator to perform a user-defined conversion. To do that, use a cast expression. As the preceding example shows, you need to compare the result of the as expression with null to check if the conversion is successful. A cast expression of the form T E performs an explicit conversion of the result of expression E to type T.

If no explicit conversion exists from the type of E to type T , a compile-time error occurs.