c++ - Nontype template class member specialization -

consider following c++ code:

template <int k> struct kdata {    float data[k]; };  template<int k> class kclass { public:        typedef kdata<k> data;     data m_data;      data square()     {         data result;         for(int = 0; < k; ++i)             result.data[i] = m_data.data[i] * m_data.data[i];         return result;     }      // specialization k = 2     template<>     kclass<2>::data square(); };  template<> kclass<2>::data kclass<2>::square() {    data result;    result.data[0] = m_data.data[0] * m_data.data[0];    result.data[1] = m_data.data[1] * m_data.data[1];    return result; }  int main() {    kclass<2> c;    c.m_data.data[0] = c.m_data.data[1] = 1.f;    c.square();     return 0; } 

it has 'kcalss' has template data member ('m_data') , method performs computations on data member ('square()'). want make specialization of 'square()' case when k = 2, example.

trying compile 4.6.7 or 4.7.2 gives following error:

main.cpp:23:14: error: explicit specialization in non-namespace scope 'class kclass'

main.cpp:24:5: error: 'data' in 'class kclass<2>' not name type

any idea of i'm doing wrong?

thanks in advance.

=== edit ===

a workaround found declare second 'square()' method template well:

template<int k2> typename kclass<k2>::data square(); 

it works nicely, allows user call 'aquare()' passing template parameter different class, e.g:

kclass<2> c; c.square<3>; 

which gives "undefined reference to" linking error.

=== edit (solution) ===

all right, solution simpler expected. had remove template declaration:

template<> inline kclass<2>::data square(); 

, unnecessary.

template<> kclass<2>::data kclass<2>::square()                 ^^^^^^^^ { 

---

and have remove this. not how specialize member function. member function can not specialized in class scope. needs specialized within surrounding namespace of class declaration.

 template<>  kclass<2>::data square();