loadlibrary from dll

hey guys,

ist it possible to use LoadLibrary from inside a dll file to get access to another dll?

part of sorcecode:

Code:

#include <string.h>
#include <stdio.h>
#include <windows.h>

.
.
.

extern "C" void __declspec(dllexport) __cdecl EXPORTNAME
(float *a,int *b, char *c, char *d, char *e)

{
typedef void (_cdecl *MYPROC)(double*, double*); 

HINSTANCE hinstlib_ctrl;

MYPROC call_controller;

hinstlib_ctrl = LoadLibrary("DLLNAME.dll"); // compiler ERROR in this LINE 

//call_controller=(MYPROC)GetProcAddress(hinstlib_ct rl,"Controller"); 

.
.
.

maybe anyone has an answer!

thank you

Instead of asking "is this possible," why not provide us with the compiler error?

Code:

error C2664: 'LoadLibraryW' : cannot convert parameter 1 from 'const char [17]' to 'LPCWSTR'
1>        Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast

is the error message posted by VC++08.

I was asking, whether it is possible, because i am not sure, if you can use the loadlibrary in a dll.

All topics I read about where concerning executables.

The error tells you that you are building a unicode version but passing the parameters for the ascii version to LoadLibrary
try

Code:

hinstlib_ctrl = LoadLibrary(_T("DLLNAME.dll"));

Kurt

thanks for the answer, kurt

i got better indeed, the long error message is gone, but now
the message is

Code:

 error C3861: '_T': identifier not found

Do I have to include further loadlibrary functions?

I don't work on windows much but I think you have to #include <tchar.h> or something like this.
Kurt

Kurt is correct; you need to #include <tchar.h>

In the future, when you get an error when you're compiling, and you need help figuring it out, then you come here and post the EXACT error message you're receiving.

Now, this is a good discussion on WinAPI and Unicode, so you should probably go there and read.

If you don't want the extra include, the other (MS visual studios specific) way of turning a c-string into a LPCWSTR is by putting an L in front of it. So LoadLibrary(L"theDll.dll"); should work.

Thx a lot for all your help:

Of course the additional L was the correct answer.
Didn't work at first though.

The problem was a corrupted windows.h import from vs2008.
Reinstalling it fixed the problem.

Thx again for your help

The problem was a corrupted windows.h import from vs2008.

Um...how exactly do you import a header file?

Originally Posted by Cogman

If you don't want the extra include, the other (MS visual studios specific) way of turning a c-string into a LPCWSTR is by putting an L in front of it. So LoadLibrary(L"theDll.dll"); should work.

this will work only when compiling as UNICODE

_T or TEXT macros work in both cases - for UNICODE they add L, for non-UNICODE they do nothing

Originally Posted by Bubba

Um...how exactly do you import a header file?

Actually "import" is maybe the wrong expression.

Compiling the cpp file didnt't work using the old vs2008 installation (though it was the same windows.h used)

After reinstalling vs2008 the USE (maybe that's a better term) of the windows.h worked without any problems.

Why this thread is not in Win32 forum?

Make sure you are not calling the second DLL from within the first DLLs DLLMain() function, it may result in undefined behaviour.

That is; LoadLibrary() is not safe to be used within a DLLMain() function.