Error Report

Error String Display

The function GetLastError() returns a binary value that is meaningful only to people who have arguments over undocumented functions and the values returned in processor registers. For us (somewhat) more normal types, a string is much more useful. That’s where FormatMessage comes in. It will convert an error code into a language specific string.

CString csGetLastErrorString()
    {
    CString   csReturn;
    LPVOID lpMsgBuf;
    FormatMessage(
        FORMAT_MESSAGE_ALLOCATE_BUFFER |
        FORMAT_MESSAGE_FROM_SYSTEM |
        FORMAT_MESSAGE_IGNORE_INSERTS,
        NULL,
        GetLastError(),
        MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), // Default language
        (LPTSTR) &lpMsgBuf,
        0,
        NULL
        );

    // Copy the error string into our return string.

    csReturn = (TCHAR*)lpMsgBuf;

    // The FormatMessage allocated this for us so we have to release it.

    LocalFree( lpMsgBuf );
    return csReturn;
    }

Linker Problems

fcs42.lib(dllmodul.obj) : error LNK2005: _DllMain@12 already defined in MSVCRT.lib(dllmain.obj)
mfcs42.lib(dllmodul.obj) : error LNK2005: __pRawDllMain already defined in CorLock.obj
mfcs42.lib(dllmodul.obj) : warning LNK4006: _DllMain@12 already defined in MSVCRT.lib(dllmain.obj); second definition ignored
mfcs42.lib(dllmodul.obj) : warning LNK4006: __pRawDllMain already defined in CorLock.obj; second definition ignored

The basic problem here is a conflict between libraries. In general, MFC libraries must be linked before CRT libraries.

Open the Project Settings dialog box by clicking Settings on the Build menu.
Click the Link tab.
Select Input in the Category combo box.
In the Libraries to the Ignore edit box and insert the conflicting library names. In this case, the conflict is coming from MSVCRT.lib and mfcs42.lib so we’ll tell the linker to ignore these particular libraries as part of its default link list.
If we were to quit at this point and relink, we’d still have a link time failure due to unresolved link errors. To get around that, we now we want to tell the linker to include the libraries but we want to make sure that they get included in a particular order. In the Object/library Modules edit box, insert the library names. You must ensure that these are listed in order and as the first two libraries in the line (for example, mfcs42.lib MSVCRT.lib).