instantiation

I am hardly trying to create a simple application with a top menu and a changeable view below (by pressing the buttons in the menu fragment we change the view of the fragment below). So, I have 2 fragments inside the main view but when trying to run the application in the emulator I get an error like: Cause by android.app (bla bla bla, piece of crap Eclipse doesn't even allow copying the errors): Trying to instantiate a class com.example.android.topmenu that is not a fragment So, these are my XML layouts: main.xml <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http:/

It's an exercise from C++ Primer 5th Edition : Exercise 16.27: For each labeled statement explain what, if any, instantiations happen. If a template is instantiated, explain why; if not, explain why not. P.677 template <typename T> class Stack { }; void f1(Stack<char>); // (a) class Exercise { Stack<double> &rsd; // (b) Stack<int> si; // (c) }; int main() { Stack<char> *sc; // (d) f1(*sc); // (e) int iObj = sizeof(Stack< string >); // (f) } Below is what I tried: (a) Stack<char> is instantiated , but no member of it is instantiated. (b) Stack<double> is instantiated , but no member of it is

I (vaguely) know that a template is not instantiated if it is not used . For example, the following code will compile fine even though T::type doesn't make sense when T = int . template<typename T> struct A { void f() { using type = typename T::type; } }; A<int> a; //ok It compiles because f() is not used , so it is not instantiated — thus the validity of T::type remains unchecked. It doesn't matter if some other member function g() calls f() . template<typename T> struct A { void f() { using type = typename T::type; } void g() { f(); } //Is f() still unused? }; A<int> a; //ok This also

I have a class with several methods and there is no constructor among these methods. So, I am wondering if it is possible to call a method of a class without a creation of an instance of the class. For example, I can do something like that: NameOfClass.doMethod(x1,x2,...,xn) In general I do not see why it should be impossible. I just call a function which does something (or return some values). If it is possible, what will happen if the method sets a value for a private variable of the class. How can I reach this value? In the same way? NameOfClass.nameOfVariable It's called static variables

I want to construct an object in the stack, using C++. Do you know what is the difference between these to ways of calling the constructor (with and without parenthesis): a) MyClass object ; b) MyClass object() ; I am using MFC and when constructing the global variable for the main app, if I use the latter way, I get an exception, I thought these two ways were equivalent. Thank you guys for any information. LeopardSkinPillBoxHat This is one of those gotchas of C++. MyClass object(); is the way that a function prototype is defined in C++, so the compiler thinks you are trying to declare another