Question

I don’t know if this makes a difference, but I am using VS c++ 6.0

Linking…

vid3Dlg.obj : error LNK2001: unresolved external symbol "public: double __thiscall Image::jdlMin(double,double)" (?jdlMin@Image@@QAENNN@Z)
Debug/vid3.exe : fatal error LNK1120: 1 unresolved externals
Error executing link.exe.

I tried this also:

template  <class T> T Image::jdlMin( T a, T b ) 

and I get same error.

  //Image.h
    class Image  
    {
    public:
        Image();
        virtual ~Image();
        template <class T>  T jdlMin( T a, T b );
    }

//Image.cpp
Image::Image()
{
}

Image::~Image()
{
}    

template  <class T> T jdlMin( T a, T b )
//I tried this also:  template  <class T> T Image::jdlMin( T a, T b )
{
    return ( a < b );// ? a : b;
}


//CVid3Dlg.cpp
void CVid3Dlg::exTemplate()
{
    Image *im = new Image();
    int s=0;
    s = im->jdlMin((double)3,(double)4); //

}

Answer 1

This time, i compiled it (under VC++ 10) to test the functionality:

//Image.h

template<typename T>
class Image  
{
    public:
        Image() {};
        virtual ~Image() {};
        T jdlMin( T a, T b );
};


//Image.cpp
#include "Image.h"


template <typename T> 
T Image<T>::jdlMin( T a, T b )
{ 
 return ( a < b ); 
};


int _tmain(int argc, _TCHAR* argv[])
{

    Image<double> *im = new Image<double>();

    double s = 0.0;
    s = im->jdlMin( 3.0 , 4.0 );

    return 0;
}

Hope that helps…

Bye the way, i took a look into a good C++ documentation: “class T” and “typename T” have exactly the same meaning and behave exactly the same way… 😉