Unresolved external - c++

Question

I am having difficulty figuring out my unresolved external errors.
I have 2 different solutions that both share a core project. Solution #1 is called SnapGame and Solution #2 is called SnapEditor. The core project is called SnapCore.
My SnapGame solution is a Win32 application. It compiles, references, and links the SnapCore project with no issues.
The SnapEditor solution is a Windows Forms Application. It compiles and references the SnapCore project. However, it will not link with it properly. I get unresolved external errors any time I try to reference anything from the SnapCore project.
The SnapCore project has some GDI+ support classes. All classes in the SnapCore project are under the SnapCore namespace.
Here is the file Form1.cpp:
#include "stdafx.h"
#include "App.h"
#include "Orient.h"
using namespace SnapCore;
using namespace SnapEdit;
void Form1::Init()
{
SnapCore::Orient orient;
new App();
}
Here are the linker errors I get:
1>Form1.obj : warning LNK4248: unresolved typeref token (01000049) for 'Gdiplus.GpCachedBitmap'; image may not run
1>Form1.obj : error LNK2028: unresolved token (0A000019) "public: __clrcall SnapCore::App::App(void)" (??0App#SnapCore##$$FQAM#XZ) referenced in function "public: void __clrcall SnapEdit::Form1::InitSnapCore(void)" (?InitSnapCore#Form1#SnapEdit##$$FQ$AAMXXZ)
1>Form1.obj : error LNK2028: unresolved token (0A00001A) "public: __clrcall SnapCore::Orient::Orient(void)" (??0Orient#SnapCore##$$FQAM#XZ) referenced in function "public: void __clrcall SnapEdit::Form1::InitSnapCore(void)" (?InitSnapCore#Form1#SnapEdit##$$FQ$AAMXXZ)
1>Form1.obj : error LNK2019: unresolved external symbol "public: __clrcall SnapCore::App::App(void)" (??0App#SnapCore##$$FQAM#XZ) referenced in function "public: void __clrcall SnapEdit::Form1::InitSnapCore(void)" (?InitSnapCore#Form1#SnapEdit##$$FQ$AAMXXZ)
1>Form1.obj : error LNK2019: unresolved external symbol "public: __clrcall SnapCore::Orient::Orient(void)" (??0Orient#SnapCore##$$FQAM#XZ) referenced in function "public: void __clrcall SnapEdit::Form1::InitSnapCore(void)" (?InitSnapCore#Form1#SnapEdit##$$FQ$AAMXXZ)
1>C:\Work\PC\SnapEdit\SnapEdit\Debug\SnapEdit.exe : fatal error LNK1120: 4 unresolved externals
I can't figure out why my SnapGame solution links with no troubles, but the SnapEditor solution will not.
Any help would be appreciated.

Answer 1

If I understand you right, SnapEditor is a managed application. It can't simply refer to a native library, like SnapCore. Use P/Invoke, or write a managed wrapper.