Compiling a working 32bit .dll for 64bit, errors - windows

Question

I have with a lot of help put together a 32bit plugin (.dll) for the 32bit Teamspeak program which works great.
People are now asking me to compile this for the 64bit Teamspeak client.
But...........
When I do I get the following errors.
1>------ Build started: Project: GetFSComFreqs, Configuration: Release x64 ------
Creating library C:\Users\Roo\Desktop\pluginsdk\src\x64\Release\GetFSComFreqs.lib and object C:\Users\Roo\Desktop\pluginsdk\src\x64\Release\GetFSComFreqs.exp
GetFSComFreqs.obj : error LNK2019: unresolved external symbol SimConnect_Close referenced in function "void __cdecl DLLStop(void)" (?DLLStop##YAXXZ)
GetFSComFreqs.obj : error LNK2019: unresolved external symbol SimConnect_Open referenced in function "void __cdecl DLLStart(void)" (?DLLStart##YAXXZ)
SimConnectProcs.obj : error LNK2001: unresolved external symbol SimConnect_Open
GetFSComFreqs.obj : error LNK2019: unresolved external symbol SimConnect_CallDispatch referenced in function "void __cdecl DLLStart(void)" (?DLLStart##YAXXZ)
SimConnectProcs.obj : error LNK2019: unresolved external symbol SimConnect_AddToDataDefinition referenced in function "void __cdecl OnRecvOpen(struct SIMCONNECT_RECV_OPEN *,unsigned long,void *)" (?OnRecvOpen##YAXPEAUSIMCONNECT_RECV_OPEN##KPEAX#Z)
SimConnectProcs.obj : error LNK2019: unresolved external symbol SimConnect_RequestDataOnSimObject referenced in function "void __cdecl OnRecvOpen(struct SIMCONNECT_RECV_OPEN *,unsigned long,void *)" (?OnRecvOpen##YAXPEAUSIMCONNECT_RECV_OPEN##KPEAX#Z)
SimConnectProcs.obj : error LNK2019: unresolved external symbol SimConnect_GetNextDispatch referenced in function "unsigned int __cdecl MessageRoutine(void *)" (?MessageRoutine##YAIPEAX#Z)
C:\Users\Roo\Desktop\pluginsdk\src\x64\Release\GetFSComFreqs.dll : fatal error LNK1120: 6 unresolved externals
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========
A part of the Code...
#include "stdafx.h"
#define FSAPI __stdcall
HANDLE hSimConnect = 0;
HANDLE hMsgThread = 0;
HINSTANCE ThisModule = 0;
HRESULT hr = 0;
char ThisModuleName[MAX_PATH];
void FSAPI StartSimConnect()
{
if (NULL == hSimConnect)
{
GetModuleFileName(ThisModule, ThisModuleName, MAX_PATH);
hr = SimConnect_Open(&hSimConnect, ThisModuleName, NULL, NULL, NULL, 0);
hr = SimConnect_CallDispatch(hSimConnect, SimConnectDispatch, NULL);
if (FAILED(hr)) hSimConnect = 0;
else hMsgThread = (HANDLE)_beginthreadex(NULL, NULL, MessageRoutine, NULL, NULL, NULL);
}
}
void FSAPI StopSimConnect()
{
if (NULL != hSimConnect)
{
hr = SimConnect_Close(hSimConnect);
hSimConnect = 0;
}
}
int main() {}
void FSAPI DLLStart(void)
{
if (NULL == hSimConnect)
{
GetModuleFileName(ThisModule, ThisModuleName, MAX_PATH);
hr = SimConnect_Open(&hSimConnect, ThisModuleName, NULL, NULL, NULL, 0);
hr = SimConnect_CallDispatch(hSimConnect, SimConnectDispatch, NULL);
if (FAILED(hr)) hSimConnect = 0;
else hMsgThread = (HANDLE)_beginthreadex(NULL, NULL, MessageRoutine, NULL, NULL, NULL);
}
}
void FSAPI DLLStop(void)
{
if (NULL != hSimConnect)
{
hr = SimConnect_Close(hSimConnect);
hSimConnect = 0;
}
}

Answer 1

You are getting unresolved external symbols errors.
If all those SimConnect_* functions are coming from an external source, you need to link you program with the appropriate import library.
If you just changed the build configuration from win32 to x64, it might be the case that these import libraries were not changed into your x64 configuration.