Unresolved External In Class In VC++ 2008

I am trying to write a new class for performing some functions.
Basically I am writing a ECC math class.

I declared a variable as :

ECC a;
a.InitEllipticCurve(a, b, prime); //This is where i get the Unresolved external.

I've included the ECC.h file..

Here is the error :

1>Source.obj : error LNK2019: unresolved external symbol "public: void __thiscall ECC::InitEllipticCurve(__int64,__int64,__int64)" (?InitEllipticCurve@ECC@@QAEX_J00@Z) referenced in function _main

I am new to C++ & I cant understand the reason of this error, which I think is a linker error.

Best Regards
KKR

Is EEC for external library? If so, you need to add its .lib file under linker additional input files (see project properties -> linker).
If it's a source file in your project, then make sure to add all its .cpp files to your project.

ECC is a class that I am writing from scratch.
It has only one cpp file, ECC.cpp.

I've added the ECC.h in my project, do I need to add the ECC.cpp too ?

Yes, you do. You need to add all your source files to the project.
Header files are optional, but recommended.

lol.. Now the list of errors is even greater :p

1>------ Build started: Project: ECLibrary, Configuration: Debug Win32 ------
1>Compiling...
1>Source.cpp
1>Linking...
1>ECC.obj : error LNK2005: "public: __thiscall ECC::ECC(void)" (??0ECC@@QAE@XZ) already defined in Source.obj
1>ECC.obj : error LNK2005: "__int64 __cdecl ModInverse(__int64,__int64)" (?ModInverse@@YA_J_J0@Z) already defined in Source.obj
1>ECC.obj : error LNK2005: "void __cdecl InitEllipticCurve(__int64,__int64,__int64)" (?InitEllipticCurve@@YAX_J00@Z) already defined in Source.obj
1>ECC.obj : error LNK2005: "void __cdecl ECGetPoints(__int64,__int64)" (?ECGetPoints@@YAX_J0@Z) already defined in Source.obj
1>ECC.obj : error LNK2005: "void __cdecl DoubleECPoints(void)" (?DoubleECPoints@@YAXXZ) already defined in Source.obj
1>ECC.obj : error LNK2005: "public: __thiscall ECC::~ECC(void)" (??1ECC@@QAE@XZ) already defined in Source.obj
1>ECC.obj : error LNK2005: "__int64 sumY" (?sumY@@3_JA) already defined in Source.obj
1>ECC.obj : error LNK2005: "bool Infinity" (?Infinity@@3_NA) already defined in Source.obj
1>ECC.obj : error LNK2005: "__int64 a" (?a@@3_JA) already defined in Source.obj
1>ECC.obj : error LNK2005: "__int64 YCoordinate" (?YCoordinate@@3_JA) already defined in Source.obj
1>ECC.obj : error LNK2005: "__int64 b" (?b@@3_JA) already defined in Source.obj
1>ECC.obj : error LNK2005: "__int64 doubledY" (?doubledY@@3_JA) already defined in Source.obj
1>ECC.obj : error LNK2005: "__int64 XCoordinate" (?XCoordinate@@3_JA) already defined in Source.obj
1>ECC.obj : error LNK2005: "__int64 doubledX" (?doubledX@@3_JA) already defined in Source.obj
1>ECC.obj : error LNK2005: "__int64 P" (?P@@3_JA) already defined in Source.obj
1>ECC.obj : error LNK2005: "__int64 sumX" (?sumX@@3_JA) already defined in Source.obj
1>Source.obj : error LNK2019: unresolved external symbol "public: void __thiscall ECC::InitEllipticCurve(__int64,__int64,__int64)" (?InitEllipticCurve@ECC@@QAEX_J00@Z) referenced in function _main
1>C:\Users\Priyabrata\Documents\Visual Studio 2008\Projects\ECLibrary\Debug\ECLibrary.exe : fatal error LNK1120: 1 unresolved externals
1>Build log was saved at "file://c:\Users\Priyabrata\Documents\Visual Studio 2008\Projects\ECLibrary\ECLibrary\Debug\BuildLog.h tm"
1>ECLibrary - 18 error(s), 0 warning(s)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

Now what ? :p

Would you mind showing your includes for Source.cpp?

[C++] ECC.h: ------ #include <windows.h> #pragma once class ECC { public: ECC( - Pastebin.com

here you go :)

Remove #include "ECC.cpp".

Then the original problem remains..

1>Source.obj : error LNK2019: unresolved external symbol "public: void __thiscall ECC::InitEllipticCurve(__int64,__int64,__int64)" (?InitEllipticCurve@ECC@@QAEX_J00@Z) referenced in function _main

Looking over the source, here are your problems:

void ECC::InitEllipticCurve(__int64 A, __int64 B, __int64 Prime)

Add part in red.
Similarly for DoubleECPoints and ECGetPoints.
Do not include source files.

Also suggest:
Get rid of conio.h. It isn't used and it isn't standard.
Replace __int64 with long long.
Add declaration for ModInverse.
Work on getting rid of those globals.

So why did this error occur? Basically, you told the compiler that there was a member function InitEllipticCurve. But really there wasn't. It was global and not part of the class. So the linker couldn't find it, which means it couldn't create a functional program, hence the error.

Indeed, including source files is a Bad Thing.

The compiler needs to know about functions defined in other source files (since the compiler does 1 source file at a time). That's exactly what a header file is for: and your header is fine.

The linker matches up references to definitions. In this case, you hadn't defined any of the functions declared in your header file, because as Elysia points out, the functions you defined aren't members of the ECC class without the ECC:: prefix.

Doesn't help :(

Now my ECC.h reads as :

Code:

---

#include <windows.h>
#pragma once
class ECC
{
public:
        ECC(void);
    void ECC::InitEllipticCurve(__int64 A, __int64 B, __int64 Prime);
        void ECC::DoubleECPoints();
        void ECC::ECGetPoints(__int64 xcoordinate, __int64 ycoordinate);
        ~ECC(void);
};

---

1>------ Build started: Project: ECLibrary, Configuration: Release Win32 ------
1>Compiling...
1>Source.cpp
1>Compiling...
1>ECC.cpp
1>Linking...
1>Source.obj : error LNK2001: unresolved external symbol "public: void __thiscall ECC::InitEllipticCurve(__int64,__int64,__int64)" (?InitEllipticCurve@ECC@@QAEX_J00@Z)
1>C:\Users\Priyabrata\Documents\Visual Studio 2008\Projects\ECLibrary\Release\ECLibrary.exe : fatal error LNK1120: 1 unresolved externals
1>Build log was saved at "file://c:\Users\Priyabrata\Documents\Visual Studio 2008\Projects\ECLibrary\ECLibrary\Release\BuildLog .htm"
1>ECLibrary - 2 error(s), 0 warning(s)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

Your ECC.h was fine before.

It is your ECC.cpp that you need to make the modification to

I've got it :)
Now it seems to be working :)
Thanx a bunch guys :)