how to define const double in a templated class

[PengYu.UT]

Hi,

The following code does not work. Is anyway to make this work?

Thanks,
Peng

enum dirflags {
deg0,
deg45,
deg90,
deg135,
deg180,
deg_135,
deg_90,
deg_45,
N
};

template <dirflags I>
struct angle {
const double theta = I * M_PI / N;
};

 

[Alf P. Steinbach]

* (e-mail address removed):

The following code does not work. Is anyway to make this work?

Thanks,
Peng

enum dirflags {
deg0,
deg45,
deg90,
deg135,
deg180,
deg_135,
deg_90,
deg_45,
N
};

template <dirflags I>
struct angle {
const double theta = I * M_PI / N;
};

You can't define the value of a non-integral constant in the class
definition, nobody really know why.

But you can define the value separately:

template< dirflags I >
struct angle { static double const theta; }

template< dirflags I >
double angle<I>::theta = I* M_PI / N;

Note that M_PI is not a standard.

Cheers, & hth.,

- Alf