Mastering C++ Multithreading

Static order of initialization

Static variables are variables which are declared only once, essentially existing in a global scope, though potentially only shared between instances of a particular class. It's also possible to have classes which are completely static:

class Foo { 
   static std::map<int, std::string> strings; 
   static std::string oneString; 
 
public: 
   static void init(int a, std::string b, std::string c) { 
         strings.insert(std::pair<int, std::string>(a, b)); 
         oneString = c; 
   } 
}; 
 
 
std::map<int, std::string> Foo::strings; 
std::string Foo::oneString; 

As we can see here, static variables along with static functions seem like a very simple, yet powerful concept. While at its core this is true, there's a major issue which will catch the unwary ...