Re: DLL function loading issue
"--== Alain ==--" <nospam@noemail.com> wrote in message
news:%23u3hXPL5GHA.4064@TK2MSFTNGP03.phx.gbl
I have an issue with loading a function from my DLL.
here is the DLL *.cpp file :
extern "C" __declspec(dllexport) LPTSTR GetString(int Index)
{
LPTSTR res="";
LoadString(GetModuleHandle(NULL),Index, res, sizeof(res));
return(_T(res));
}
Be aware that GetModuleHandle(NULL) returns an instance handle of the
EXE your DLL is loaded into, _not_ the DLL itself. If you hope to load
the string from the DLL's resources, this code does not do that.
LoadString epxects a pointer to an existing memory buffer as the third
parameter - it does not allocate memory for you. You are giving it a
pointer to read-only memory buffer of length 1, and lie about this
buffer's size. sizeof(res) is always 4 on 32-bit system - it's the size
of the pointer, not the size of the memory it points to.
_T("x") is a macro that expands to "x" in ANSI build, and to L"x" in
Unicode build. It only makes sense to apply it to a string literal. If
you try to build Unicode build, you'll see an error on _T(res)
All in all, the code in GetString function does not make much sense.
here is my class which should load the DLL and open the function :
*.cpp file :
HINSTANCE CARDLLWrapper::InitializeLoc(CString DLLName)
{
m_hlibLoc=LoadLibrary(DLLName);
if (m_hlibLoc != NULL)
{
LocGetString = (LPTSTR)GetProcAddress(m_hlibLoc, TEXT("GetString"));
LocGetString is not of type LPTSTR, so why do you cast the return value
of GetProcAddress to LPTSTR? Shouldn't you cast to the same type
LocGetString is declared with?
static LPTSTR (*LocGetString)(long);
GetString takes an int parameter. Why do you declare LocGetString to
take a long?
--
With best wishes,
Igor Tandetnik
With sufficient thrust, pigs fly just fine. However, this is not
necessarily a good idea. It is hard to be sure where they are going to
land, and it could be dangerous sitting under them as they fly
overhead. -- RFC 1925