Solved

error after return from dll.

Posted on 2003-11-12
10
671 Views
Last Modified: 2012-06-27
I have this code:
////////////////////////
#include "stdafx.h"
typedef UINT (CALLBACK* LPFNDLLFUNC1)(DWORD,UINT);

int APIENTRY WinMain(HINSTANCE hInstance,
                     HINSTANCE hPrevInstance,
                     LPSTR     lpCmdLine,
                     int       nCmdShow)

{

HINSTANCE hDLL;               // Handle to DLL
LPFNDLLFUNC1 lpfnDllFunc1;    // Function pointer
DWORD dwParam1;
UINT  uParam2=0, uReturnVal=0;

hDLL = LoadLibrary("azza");
if (hDLL != NULL)
{
   lpfnDllFunc1 = (LPFNDLLFUNC1)GetProcAddress(hDLL,"test2");
   if (!lpfnDllFunc1)
   {
      // handle the error
      FreeLibrary(hDLL);
      MessageBox(0,"error","error",0);
   }
   else
   {
      // call the function
      uReturnVal = lpfnDllFunc1(dwParam1, uParam2);
   }
}
return 0;
}
//////////////////////////

which calls function test2 in azza.dll.
When I run the program, the function is executed, but after the execution of the function, I have the following error:


/////////////////
---------------------------
Microsoft Visual C++ Debug Library
---------------------------
Debug Error!

Program: ... Files\Microsoft Visual Studio\MyProjects\user\Debug\user.exe
Module:
File: i386\chkesp.c
Line: 42

The value of ESP was not properly saved across a function call.  This is usually a result of calling a function declared with one calling convention with a function pointer declared with a different calling convention.

(Press Retry to debug the application)
---------------------------
Afbreken   Opnieuw   Negeren  
---------------------------
/////////////////////

I'm new to c++. What does this error means, and how should I solve it ??
0
Comment
Question by:plinius
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10 Comments
 
LVL 86

Expert Comment

by:jkr
ID: 9736684
>>The value of ESP was not properly saved across a function call

This means that either the parameter list or the calling convention for "test2()" don't match in both projects.
0
 
LVL 6

Expert Comment

by:GloomyFriar
ID: 9738657
Show how the test2 function is declared in the dll.
0
 
LVL 6

Assisted Solution

by:GloomyFriar
GloomyFriar earned 65 total points
ID: 9738672
Try to do so:

in dll:
extern "C"  UINT __declspec(dllexport) test2(DWORD,UINT);

in exe:
typedef UINT (__cdecl *LPFNDLLFUNC1)(DWORD,UINT);
0
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Author Comment

by:plinius
ID: 9738778
this is my dll.
/////////////////
// azza.cpp : Defines the entry point for the DLL application.
//

#include "stdafx.h"
#include <iostream>

using namespace std;

extern "C" __declspec(dllexport)void test2();

BOOL APIENTRY DllMain( HANDLE hModule,
                       DWORD  ul_reason_for_call,
                       LPVOID lpReserved
                               )
{
    return TRUE;
}


void test2(){MessageBox(0,"test2","hallo",0);}
////////////////
0
 
LVL 86

Accepted Solution

by:
jkr earned 75 total points
ID: 9739691
Well, that is the problem:

typedef UINT (CALLBACK* LPFNDLLFUNC1)(DWORD,UINT);

and

extern "C" __declspec(dllexport)void test2();

simply do _not_ match - use either

typedef void (*LPFNDLLFUNC1)();

or

extern "C" __declspec(dllexport) UINT CALLBACK test2(DWORD,UINT);


0
 

Author Comment

by:plinius
ID: 9740370
thanks.
0
 
LVL 86

Expert Comment

by:jkr
ID: 9740419
Don't want to be picky, but in which way did I 'assist'? I consider the following the answer:

Comment from jkr  Date: 11/13/2003 02:39AM GMT  
>>The value of ESP was not properly saved across a function call

This means that either the parameter list or the calling convention for "test2()" don't match in both projects.  
0
 

Author Comment

by:plinius
ID: 9742637
actually, this didn't assisted (I don't know what ESP & calling convention are, since I'm actually Dutch). It was
"
Well, that is the problem:
typedef UINT (CALLBACK* LPFNDLLFUNC1)(DWORD,UINT);
and
extern "C" __declspec(dllexport)void test2();
simply do _not_ match - use either
typedef void (*LPFNDLLFUNC1)();
or
extern "C" __declspec(dllexport) UINT CALLBACK test2(DWORD,UINT);

"
that helped me.
0
 
LVL 86

Expert Comment

by:jkr
ID: 9743051
So, that was still me :o)
0
 
LVL 6

Expert Comment

by:GloomyFriar
ID: 9746697
Hey, jkr, do you want to say, that my suggestion is wrong?
0

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