` C++ Calling clarion functions from VC (Jim Kane) - Icetips Article
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Other Languages - using Clarion with...: C++ Calling clarion functions from VC
2002-11-28 -- Jim Kane
 
Newsgroups: comp.lang.clarion I wrote a clarion dll to read tps files from vc. I did not use (I never use) mfc or atl. This was a straight C app. in callfile.c case WM_CREATE: hInstance = ((LPCREATESTRUCT) lParam)->hInstance; hdc = GetDC (hwnd) ; GetTextMetrics (hdc, &tm) ; cxChar = tm.tmAveCharWidth ; cxCaps = (tm.tmPitchAndFamily & 1 ? 3 : 2) * cxChar / 2 ; cyChar = tm.tmHeight + tm.tmExternalLeading ; ReleaseDC (hwnd, hdc) ; //load the clarion dll hGetFile = LoadLibrary(TEXT("GETFILE.DLL")); if(!hGetFile == 0) { PD_Init = )GetProcAddress(hGetFile,"PD_INIT"); PD_SetDataPath = D_SETDATAPATH )GetProcAddress(hGetFile,"PD_SETDATAPATH"); PD_GetBufferSize = (PD_GETBUFFERSIZE )GetProcAddress(hGetFile,"PD_GETBUFFERSIZE"); PD_OpenFile = PENFILE )GetProcAddress(hGetFile,"PD_OPENFILE"); //more code here } else { MessageBox(hwnd,"LoadLib Failed for GetFile.dll","Fatal Error", MB_OK); SendMessage(hwnd,WM_CLOSE,0,0); return(1); } if(PD_Init == 0 || PD_SetDataPath==0 || PD_OpenFile==0 || PD_GetBufferSize==0 || //more code here ) { MessageBox (hwnd, TEXT("Wrong version of GetFile.Dll"), TEXT("Fatal Error"), MB_OK); SendMessage(hwnd,WM_CLOSE,0,0); return(1); } PD_Init(); //Init the dll //rest of the program here...... then in callfile.h the prototypes #ifndef CALLFILE_H #define CALLFILE_H #ifdef __cplusplus extern "C" { #endif //Function Prototypes typedef void (WINAPI * PD_INIT)(void); PD_INIT PD_Init; typedef unsigned char (WINAPI * PD_SETDATAPATH )(LPCSTR lpDataPath); PD_SETDATAPATH PD_SetDataPath; typedef unsigned char (WINAPI * PD_GETBUFFERSIZE)(LPCSTR lpFileLabel, LPDWORD cbBuffer); PD_GETBUFFERSIZE PD_GetBufferSize; typedef unsigned char (WINAPI * PD_OPENFILE)(LPCSTR lpFileLabel, LPCVOID lpBuffer, DWORD cbBuffer); PD_OPENFILE PD_OpenFile; typedef unsigned char (WINAPI * PD_CLOSEFILE)(LPCSTR lpFileLabel); PD_CLOSEFILE PD_CloseFile; //other prototypes here //Equates // Error Equates - Usually returned as a byte (unsigned char) #define levelbenign 0 //No Error #define levelfatal 3 //Error - Action did not complete #define levelnotify 5 //Action didnt complete but not an error - typically End of File //Cstring size for File and Key Labels #define LabelLen 41 #ifdef __cplusplus }; #endif #endif Jim Kane "Mihai Palade (Bucharest - Romania)" wrote in message news:3de5e21a@news.softvelocity.com... > Hi, > > I have changed the name attribute as '_cwhello' ! I am getting exactly the > same link error ! > The lib is the one generated by Clarion. > Inside MSDN they say that LoadLibrary is another solution. > What I am using impluies that CWHELLO is inside CWHELLO.DLL . (!?). > As I said, I am very unexperienced here, I just wanna make a call from VC++ > to Clarion. > If possible and have some time, could you prepare for me a very simple > example !? > Thank you for your time ! > > Mihai > > "jim kane" wrote in message > news:3de5b668$1@news.softvelocity.com... > > change the name attribute to name('_cwhello') > > that is what vc is looking for. > > I dont know how you have made a lib for VC to link - usually I call by > > address to call a cw dll. I use loadlibrary, getprocaddress() and call by > > address. > > jim kane > > > > "Mihai Palade" wrote in message > > news:3de56c88@news.softvelocity.com... > > > Hello, > > > > > > No experience with VC++. I just wanna try if VC++ may call a Clarion DLL > : > > > > > > 1) I have a C55 DLL which exports a function > > > CWHELLO - (REAL),REAL,C,NAME('CWHELLO') - it just shows up an HELLO > > message > > > box. > > > > > > 2) VC++ has to call the CWHELLO function > > > > > > QUESTION : What is the function prototype I have to use !? > > > > > > extern "C" double CWHELLO(double); (!!!???); in this case the compile > > works > > > but I am having problems with the linker : > > > > > > Linking... > > > simpleCALL.obj : error LNK2001: unresolved external symbol _cwhello > > > Debug/simpleCALL.exe : fatal error LNK1120: 1 unresolved externals > > > Error executing link.exe. > > > > > > Mihai > > > > > > > > > > > >


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