static constant - non integral type

Code:

---


// header file called .. test.h                [1]
static const double dval ( 3.1233 );

// in a source file called main.cpp        [2]
class  bar {
  static const double dbar_val ;
public :
  bar () {}


};


double bar::dbar_val = 3.1233;

---

[1] compiles while [2] does not because only (hope I'm saying this right) static const integral data members can be initialized in a class. I was reading a thread a few days ago where it was said - if memory serves - C++Ox (some version of GCC is already doing this) will recognize [2]. The question: Why is [1] allowed to compile while [2] doesnt? The fact that one is a class and the other is not doesnt seem like a good answer to me.

The problem here is simply that dbar_val is declared const but defined non-const. Change that line to:

Code:

---

const double bar::dbar_val = 3.1233;

---

Note you could also do:

Code:

---

class  bar {
  static const double dbar_val = 3.1233;
public :
  bar () {}
};

const double bar::dbar_val;

---

I should add that static class member definitions should always appear in a cpp (or equivalent) file, never in a header unless it is a template class.

Thanks Hermit. That was a bonehead move on my part.