VS.NET - non-type template classes with FLOAT

Posted on 2003-11-12
Last Modified: 2010-04-02

I am having a problem compiling one of my projects (VS.NET, project imported from VC6), because there is a problem with how VS.NET handles FLOATS in non-type template classes. I have checked out MSDN : BUT no joy as it says if it is a class template which mine is, there is no easy workaround.

So to my question, does anyone know of a way to solve this ? I am thinking that i will have to write a new class to include the float parameters only, and take them out of the template class. Is this the correct way ? For your info, below is my template class.

template<class T, TypeID_gem_t TypeID, T Invalid>
class CGEM_ArrayItem : public CGEM_DataItem
      LPCSTR      m_pszName;
      T*            m_pVal;
      size_t      m_cElemCount;
      TypeID_gem_t m_type;

       CGEM_ArrayItem(const TGEM_DATA_DEF& DataDef)  
             : m_cElemCount(DataDef.ItemCount),

            m_pVal = new T[m_cElemCount];

            if(m_pVal == 0)
                  m_cElemCount = 0;
                  for(int i = 0; i < m_cElemCount; i++)
                              m_pVal[i] = Invalid;

            m_pszName = ::_strdup(DataDef.pszItemName);

            TGEM_DATA d;
            d.val = DataDef.IniVal;
            d.ParType = DataDef.ParType;


            delete[] m_pVal;

      static SAFEARRAY* GetSafeArray(const TGEM_DATA& data)
                  case GEM_I8_ARRAY:      return data.val.I8_array;
                  case GEM_I16_ARRAY:      return data.val.I16_array;                  
                  case GEM_I32_ARRAY:      return data.val.I32_array;
                  case GEM_I64_ARRAY:      return data.val.I64_array;

                  case GEM_SF_ARRAY:      return data.val.SF_array;      //singlefloat      
                  case GEM_DF_ARRAY:      return data.val.DF_array;      //doublefloat            

                  case GEM_U8_ARRAY:      return data.val.U8_array;                  
                  case GEM_U16_ARRAY:      return data.val.U16_array;                  
                  case GEM_U32_ARRAY:      return data.val.U32_array;                  
                  case GEM_U64_ARRAY:      return data.val.U64_array;                  
                  case GEM_B_ARRAY:      return data.val.B_array;                  

                        return NULL;

      HRESULT Set(const TGEM_DATA& data)
            HRESULT hr = E_INVALIDARG;
            SAFEARRAY *psa = GetSafeArray(data);

            if(psa != NULL)            
                  ULONG size = sizeof T;
                  ATLASSERT(SafeArrayGetElemsize(psa) == sizeof T);
                  void *pSrc;
                  hr = SafeArrayAccessData(psa, &pSrc);

                        long plUbound;

                        hr = SafeArrayGetUBound(psa, 1, &plUbound);

                        if(SUCCEEDED(hr) && ++plUbound == m_cElemCount)
                              memcpy(m_pVal, pSrc, plUbound * sizeof T);
                              hr = E_INVALIDARG;

            return hr;

      TypeID_gem_t      GetType() { return m_type; }
      Data_gem_t*            GetData() { return m_pVal; }
      LPCSTR                  GetName() { return m_pszName; }
      Integer32_gem_t GetElementCount() { return m_cElemCount; }

      void Invalidate()
                  for(int i = 0; i < m_cElemCount; i++)
                        m_pVal[i] = 0;

Any help would be most appreciated in this porting exercise from VS6 to VS.NET C++.

Kind Regards

Question by:upliftin
LVL 17

Accepted Solution

rstaveley earned 200 total points
Comment Utility
I think you have to pass it as a constructor parameter :-(

#include <iostream>

template<class T> class TC {
        const T initialiser;
        TC(T initialiser) : initialiser(initialiser) {}
        void print() const { std::cout << "Initialiser is " << initialiser << '\n';}

int main()
        TC<double> tc(123.456);

Expert Comment

Comment Utility
No comment has been added lately, so it's time to clean up this TA.
I will leave the following recommendation for this question in the Cleanup topic area:

Accept: rstaveley {http:#9734842}

Please leave any comments here within the next seven days.

EE Cleanup Volunteer

Featured Post

How your wiki can always stay up-to-date

Quip doubles as a “living” wiki and a project management tool that evolves with your organization. As you finish projects in Quip, the work remains, easily accessible to all team members, new and old.
- Increase transparency
- Onboard new hires faster
- Access from mobile/offline

Join & Write a Comment

Suggested Solutions

When writing generic code, using template meta-programming techniques, it is sometimes useful to know if a type is convertible to another type. A good example of when this might be is if you are writing diagnostic instrumentation for code to generat…
What is C++ STL?: STL stands for Standard Template Library and is a part of standard C++ libraries. It contains many useful data structures (containers) and algorithms, which can spare you a lot of the time. Today we will look at the STL Vector. …
The goal of the video will be to teach the user the concept of local variables and scope. An example of a locally defined variable will be given as well as an explanation of what scope is in C++. The local variable and concept of scope will be relat…
The viewer will learn how to user default arguments when defining functions. This method of defining functions will be contrasted with the non-default-argument of defining functions.

728 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

10 Experts available now in Live!

Get 1:1 Help Now