static-members

Can a template class in C++ have static members? Since it doesn't exist and is imcomplete before it is used, is this possible? Yes. The static member is declared or defined inside the template< … > class { … } block. If it is declared but not defined, then there must be another declaration which provides the definition of the member. template< typename T > class has_static { // inline method definition: provides the body of the function. static void meh() {} // method declaration: definition with the body must appear later static void fuh(); // definition of a data member (i.e., declaration

error LNK2001: unresolved external symbol "private: static class irrklang::ISoundEngine * GameEngine::Sound::_soundDevice" (?_soundDevice@Sound@GameEngine@@0PAVISoundEngine@irrklang@@A) I cannot figure out why i am receiving this error. I believe i am initializing correctly. Can anyone lend a hand? sound.h class Sound { private: static irrklang::ISoundEngine* _soundDevice; public: Sound(); ~Sound(); //getter and setter for _soundDevice irrklang::ISoundEngine* getSoundDevice() { return _soundDevice; } // void setSoundDevice(irrklang::ISoundEngine* value) { _soundDevice = value; } static bool

I'd like to have a base class that has a constant field (like an unique ID associated with the class that can't be modified after compile time). So far the static const declaration would be just fine. Now, I'd like to inherit this base class and make sure that the children of this class do have the same field, but with their own values. How can I do this? Let's say, I'd like to have a base class called Base with an ID field that holds the int value of 0. Then, I'd like to have the classes A , B and C , all of them being public children of Base and I'd like to make sure that these children

Basically, if I want to do the following: public class SomeClass { private static ConcurrentDictionary<..., ...> Cache { get; set; } } Does this let me avoid using lock s all over the place? Yes, it is thread safe and yes it avoids you using locks all over the place (whatever that means). Of course that will only provide you a thread safe access to the data stored in this dictionary, but if the data itself is not thread safe then you need to synchronize access to it of course. Imagine for example that you have stored in this cache a List<T> . Now thread1 fetches this list (in a thread safe

What is the right way to initialize static data members in C++? I'm also interested in how it has changed from C++98, to C++11 to C++14. Here is an example: // bufferedOutput.h class BufferedOutput { // Static member declaration. static long bytecount; }; // bufferedOutput.cpp long BufferedOutput::bytecount = 50; Are there other ways to initialize static data members? The rules have always been as follows: A const static data member (SDM) of integral or enumeration type can be initialised in class with a constant expression. A constexpr SDM must be initialised in class with a constant