initializer

Wiki says: The extern keyword means "declare without defining". In other words, it is a way to explicitly declare a variable, or to force a declaration without a definition. It is also possible to explicitly define a variable, i.e. to force a definition. It is done by assigning an initialization value to a variable . That means, an extern declaration that initializes the variable serves as a definition for that variable . So, /* Just for testing purpose only */ #include <stdio.h> extern int y = 0; int main(){ printf("%d\n", y); return 0; } should be valid ( compiled in C++11 ). But when

To use initialization syntax like this: var contacts = new ContactList { { "Dan", "dan.tao@email.com" }, { "Eric", "ceo@google.com" } }; ...my understanding is that my ContactList type would need to define an Add method that takes two string parameters: public void Add(string name, string email); What's a bit confusing to me about this is that the { } initializer syntax seems most useful when creating read-only or fixed-size collections . After all it is meant to mimic the initialization syntax for an array , right? (OK, so arrays are not read-only; but they are fixed size.) And naturally it

(I know) In c++ I can declare variable out of scope and I can't run any code/statement, except for initializing global/static variables. IDEA Is it a good idea to use below tricky code in order to (for example) do some std::map manipulation ? Here I use void *fakeVar and initialize it through Fake::initializer() and do whatever I want in it ! std::map<std::string, int> myMap; class Fake { public: static void* initializer() { myMap["test"]=222; // Do whatever with your global Variables return NULL; } }; // myMap["Error"] = 111; => Error // Fake::initializer(); => Error void *fakeVar = Fake:

I have some protocols LoginStrategy public protocol LoginStrategy { func login(_ viewController: UIViewController) func getUserInfo(withCompletionHandler completionHandler: @escaping (_ userInfo: [String: Any]?) -> ()) func createLoginButton(_ frame: CGRect, withCompletionHandler completionHandler: @escaping (_ loginButton: UIView) -> ()) func getUserId() -> String } and two classes: LoginProvider public class LoginProvider { public let strategy: LoginStrategy public func login(_ viewController: UIViewController) { return self.strategy.login(viewController) } public func getUserInfo

I am a new C++ user... I have a question regarding how to declare a member of a class "classA" that is an object of another class "classB", knowing that "classB" has a constructor that takes a string parameter (in addition to the default contructor). I did some research online about this issue however it did not help much to help me fix the issue I'm dealing with. To be more specific, I want to create a class that has as member a VideoCapture object (VideoCapture is an openCV class that provide a video stream). My class has this prototype : class myClass { private: string videoFileName ;