According to a duplicate question at Bytes, the typeof value unknown is added to JScript version 8, along with date. A comment to a blog by Robert Nyman can also be explanatory: Internet Explorer displays “unknown” when the object in question is on the other side of a COM+ bridge. You may not know this … Read more
As I understand it, NaN is a sentinel instance of the Number class that represents, well, exactly what it stands for – numeric results that cannot be adequately represented. So 0/0 is not a number, in the sense that it’s NaN, but it is a Number in terms of its type. Perhaps it should have … Read more
To answer the main question – there is no danger in using typeof with ==. Below is the reason why you may want to use === anyway. The recommendation from Crockford is that it’s safer to use === in many circumstances, and that if you’re going to use it in some circumstances it’s better to … Read more
This code showed me the different TypeNames that were in my Inbox: Public Sub GetTypeNamesInbox() Dim myOlItems As Outlook.Items Set myOlItems = application.GetNamespace(“MAPI”).GetDefaultFolder(olFolderInbox).Items Dim msg As Object For Each msg In myOlItems Debug.Print TypeName(msg) ’emails are typename MailItem ‘Meeting responses are typename MeetingItem ‘Delivery receipts are typename ReportItem Next msg End Sub HTH
String from an instance: String(describing: self) String from a type: String(describing: YourType.self) Example: struct Foo { // Instance Level var typeName: String { return String(describing: Foo.self) } // Instance Level – Alternative Way var otherTypeName: String { let thisType = type(of: self) return String(describing: thisType) } // Type Level static var typeName: String { return … Read more
Because 0 is one of the many falsy values in javascript All these conditions will be sent to else blocks: if (false) if (null) if (undefined) if (0) if (NaN) if (”) if (“”) if (“) From the Array.prototype.filter() documentation: filter() calls a provided callback function once for each element in an array, and constructs … Read more
If you need to switch on the type of the outer interface{} you wont need reflection. switch x.(type){ case int: dosomething() } …but if you need to switch on the type of the attributes in an interface then you can do this: s := reflect.ValueOf(x) for i:=0; i<s.NumValues; i++{ switch s.Field(i).Interface().(type){ case int: dosomething() } … Read more
you can do this: IList<Person> persons = new List<Person>(); public IList<T> GetPersons<T>() where T : Person { return persons.OfType<T>().ToList(); } IList<Student> students = GetPersons<Student>(); IList<Teacher> teacher = GetPersons<Teacher>(); EDIT: added the where constraint.
C++ language has no such thing as typeof. You must be looking at some compiler-specific extension. If you are talking about GCC’s typeof, then a similar feature is present in C++11 through the keyword decltype. Again, C++ has no such typeof keyword. typeid is a C++ language operator which returns type identification information at run … Read more
If you know the actual type, then just: SomeType typed = (SomeType)obj; typed.MyFunction(); If you don’t know the actual type, then: not really, no. You would have to instead use one of: reflection implementing a well-known interface dynamic For example: // reflection obj.GetType().GetMethod(“MyFunction”).Invoke(obj, null); // interface IFoo foo = (IFoo)obj; // where SomeType : IFoo … Read more