static constant - non integral type

[mop65715]

// 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.

[Hermit]

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

const double bar::dbar_val = 3.1233;

Note you could also do:

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.

[mop65715]

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