unresolved externals

[curious2007]

I am getting the following type of error:

1>Compiling manifest to resources...
1>Linking...
1>main.obj : error LNK2019: unresolved external symbol "public: virtual __thiscall MatrixIterativeSolver<double,int>::~MatrixIterativ eSolver<double,int>(void)" (??1?$MatrixIterativeSolver@NH@@UAE@XZ) referenced in function _main

1>main.obj : error LNK2019: unresolved external symbol "public: virtual class Vector<double,int,class FullArray<double,class std::allocator<double> > > __thiscall MatrixIterativeSolver<double,int>::result(void)con st " (?result@?$MatrixIterativeSolver@NH@@UBE?AV?$Vecto r@NHV?$FullArray@NV?$allocator@N@std@@@@@@XZ) referenced in function _main

1>main.obj : error LNK2019: unresolved external symbol "public: virtual void __thiscall MatrixIterativeSolver<double,int>::solve(void)" (?solve@?$MatrixIterativeSolver@NH@@UAEXXZ) referenced in function _main

1>main.obj : error LNK2019: unresolved external symbol "public: virtual void __thiscall MatrixIterativeSolver<double,int>::setIterationTyp e(enum IterativeType)" (?setIterationType@?$MatrixIterativeSolver@NH@@UAE XW4IterativeType@@@Z) referenced in function _main

1>main.obj : error LNK2019: unresolved external symbol "public: virtual void __thiscall MatrixIterativeSolver<double,int>::setTolerance(do uble const &)" (?setTolerance@?$MatrixIterativeSolver@NH@@UAEXABN @Z) referenced in function _main

1>main.obj : error LNK2019: unresolved external symbol "public: __thiscall MatrixIterativeSolver<double,int>::MatrixIterative Solver<double,int>(class NumericMatrix<double,int,class FullMatrix<double,class std::allocator<double> > > &,class Vector<double,int,class FullArray<double,class std::allocator<double> > > &)" (??0?$MatrixIterativeSolver@NH@@QAE@AAV?$NumericMa trix@NHV?$FullMatrix@NV?$allocator@N@std@@@@@@AAV? $Vector@NHV?$FullArray@NV?$allocator@N@std@@@@@@@Z ) referenced in function _main

1>C:\Users\EK\Documents\Visual Studio 2005\Projects\vec\Debug\vec.exe : fatal error LNK1120: 6 unresolved externals

I have heard before that this unresolved external error can be caused by declaring a function and not defining it. This is not my case. However, one think that caught my attention is all the functions causing this error are virtual.

[weaknessforcats]

I have heard before that this unresolved external error can be caused by declaring a function and not defining it. This is not my case. However, one think that caught my attention is all the functions causing this error are virtual.

This is exactly your case. A LNK2019 error means your died in the link. That is, all of the files have compiled correctly. This means that you used function prototypes in your files but never compiled the functions for those prototypes.

This is odd since all of the errors are for missing template funcitons. And that can't happen unless you are misusing the templates.

Question: You have included the templates in every source file? (you should answer YES).
Question: You are not using function prototypes for template funcitons? (You should answer YES).

Be certain ALL templates are included at a global level in every source file in your program.

[curious2007]

Ok, apparently I have not included some of the hpp files. Now, the problem is solved. However, just to make this clear are you suggesting that I should include all of the hpp files in all of the cpp files in my project?

[weaknessforcats]

Header files need onl;y be include if they contain declarations used by the .cpp file.

However, it is common to package up header files into an uber-header to avoid having to include lots of header files individually.

Be sure your header all have inclusion guards (#ifndef.. #define...#endif) so they can be included multple times in the same .cpp without causing redefinition errors.

Be sure all templates are included at the global level.