An error occurred while calling the DLL code using loadlibrary and getprocaddress functions.

Use loadlibrary and getprocaddress functions to call the DLL Code If you have any questions, please kindly advise (Thank you )! Landlord
Wangzi163 (Oracle)
14:12:01 in VC/mfc/process/thread/DLL

Expert advice Program What's the problem? I made a DLL file and wanted to call it in the display mode. It was implemented using loadlibrary and getprocaddress functions, but the operation always failed.
The program code is as follows:
// Dll_test.cpp generates dll_test.dll
# Include "stdafx. H"
# Include "dll_test.h"
Int max (int A, int B)
{
If (A> B)
Return;
Else
Return B;
}
Bool apientry dllmain (handle hmodule,
DWORD ul_reason_for_call,
Lpvoid lpreserved
)
{
Switch (ul_reason_for_call)
{
Case dll_process_attach:
Case dll_thread_attach:
Case dll_thread_detach:
Case dll_process_detach:
Break;
}
Return true;
}

// Test_getmax.cpp
# Include "stdafx. H"
# Include <stdio. h>
# Include <afxwin. h>
# Include <afxext. h>
# Include <afxdisp. h>
# Include <afxdtctl. h>
Int main (INT argc, char * argv [])
{
Typedef int (callback * lpfndllfunc) (INT, INT );
Hinstance hdll;
Lpfndllfunc;

Hdll = loadlibrary ("dll_test.dll ");
If (hdll! = NULL)
{
Lpfndllfunc = (lpfndllfunc) getprocaddress (hdll, "Max ");
If (! Lpfndllfunc)
{
Freelibrary (hdll );
}
Else
{
Printf ("function found ");
Int;
A = lpfndllfunc (1, 2 );
Printf ("return straight: % d", );
}
}
Return 0;
}

Number of questions: 100, replies: 12
Top

1st Floor
Louifox)
The score is returned at 14:41:24 ,. 5

Note the folder in which dll_test.dll is located. Top

2nd floor
Oyljerry ([heartbleed] → tiramisu √ success)
The score is returned at 15:01:31 ,. 2

Ensure that the DLL is under the project directory
Error refers to what error? Top

Third floor
Legendhui (autumn leaves)
The score is returned at 15:27:24 ,. 2

Check whether your dll path is top

4th floor
Wenxinfly)
The score is returned at 15:36:54 ,. 2

The above makes sense.
But does your int max () function Add the top icon that marks the export function?

5th floor
Laiyiling (Stranger [MVP])
The score is returned at 20:31:20 ,. 50

Do not call back
Typedef int (sqrtproc) (INT, INT );
Sqrtproc * lpfndllfunc;
Lpfndllfunc = (sqrtproc *) getprocaddress (hdll, "Max"); top

6th Floor
Kugou123 (cool dog) (awesome life, do not need to explain www.xiaozhou.net)
The score is returned at 20:36:15 ,. 10

You are advised to use the. Def file for export.
Avoid the compiler changing the name of your export function.
In addition, if your function does not have a call Convention, do not add it when you use typedef to define the function pointer. Top

7 th floor
Wellin ()
The score is returned at 23:55:01 ,. 20

Typedef int (* AAA) (INT, INT );
AAA lpfndllfunc;
Hinstance hinst;
Hinst = loadlibrary ("demodll. dll ");
Lpfndllfunc = (AAA) getprocaddress (hinst, function name );
Lpfndllfunc (A, B );
Top

8 th floor
Tankbattle (tank wars)
The score is returned at 00:44:50 ,. 3

Use dumpbin.exe (available in VC) to check what function names exported from the dynamic library are changed. Top

9th floor
Redkit (chinayan)
The score is returned at 12:49:00 ,. 2

Hdll = loadlibrary ("dll_test.dll ");
In this case, you should use the absolute path!

Top

10th floor
Sambios)
The score is returned at 15:41:04 ,. 4

The code above has the following Disadvantages:
1) No description of the function to be exported.
2) The. Def file is missing.
The content of the corrected file is as follows:
Change the function in DLL to the following code:
Extern "C" _ declspec (dllexport) int _ stdcall max (int A, int B)
{
If (A> B)
Return;
Else
Return B;
}
// The content of the test. Def file is as follows:
Exports
Max
//:~
The main function does not need to be modified. So there is no problem.
Top

11 th floor
Wangzi163 (Oracle)
The score is 0 at 19:20:23.

I have already declared it, but I forgot to write it, as shown below:
Extern "C" _ declspec (dllimport) int max (int A, int B );
The last reason is to remove callback. Thank you! Top

12th floor
Robot1980 (past events)
The score is 0 at 14:47:36.

OK