Which, if any, of the following static data member declarations and definitions are errors? Explain why

    // example.h
    class Example {
    public:
      static double rate; // = 6.5;
      // static member should be initialize ouside class
      static const int vecSize = 20;
      static vector<double> vec; //(vecSize);
      // 1. cannot use parentheses as in-class initializer
      // 2. static member should be initialize ouside class
    };

    // example.C
    #include "example.h"
    double Example::rate = 6.5;
    // should initialize static data member
    vector<double> Example::vec(vecSize);
    // should initialize static data member