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i am new to creating dll and using function from them by dynamic loading....
see i made a program....and defined a function test() in that....i tried to load that...but not getting output....my files are..
----------------------------------------------------------------------------
//library header file key.h
#ifndef _DLL_H_
#define _DLL_H_
#if BUILDING_DLL
# define DLLIMPORT __declspec (dllexport)
#else /* Not BUILDING_DLL */
# define DLLIMPORT __declspec (dllimport)
#endif /* Not BUILDING_DLL */
DLLIMPORT void test( );
#endif /* _DLL_H_*/
--------------------------------------------------------------
//dllmain.cpp file
-----------------------------------------------------------------
/* Replace "dll.h" with the name of your header */
#include <windows.h>
#include "key.h"
DLLIMPORT void test( )
{
MessageBox( HWND_DESKTOP,"TEST DONE","hi",MB_OK | MB_ICONINFORMATION);
}
BOOL WINAPI DllMain(
HINSTANCE hinstDLL, // handle to DLL module
DWORD fdwReason, // reason for calling function
LPVOID lpReserved ) // reserved
{
// Perform actions based on the reason for calling.
switch( fdwReason )
{
case DLL_PROCESS_ATTACH:
MessageBox( HWND_DESKTOP,"DLL_PROCESS_ATTACH","info",MB_OK | MB_ICONINFORMATION);
break;
case DLL_PROCESS_DETACH:
MessageBox( HWND_DESKTOP,"DLL_PROCESS_DETACH","info",MB_OK | MB_ICONINFORMATION);
break;
case DLL_THREAD_ATTACH:
MessageBox( HWND_DESKTOP,"DLL_THREAD_ATTACH","info",MB_OK | MB_ICONINFORMATION);
break;
case DLL_THREAD_DETACH:
MessageBox( HWND_DESKTOP,"DLL_THREAD_DETACH","info",MB_OK | MB_ICONINFORMATION);
break;
}
return TRUE; // Successful DLL_PROCESS_ATTACH.
}
-----------------------------------------------------------------------
/my main.cpp using above library by dynamic loading....
#include <windows.h>
#include <stdio.h>
#include <winuser.h>
#include <windowsx.h>
#include <time.h>
HWND hwndMain;
HINSTANCE hinstDLL;
typedef VOID (*MYPROC)(LPTSTR); ///don't understand this....i think this should be.... typedef VOID (*MYPROC)( )..
MYPROC test;
/* Make the class name into a global variable */
char szClassName[ ] = "svc";
/* Declare Windows procedure */
LRESULT CALLBACK WindowProcedure (HWND, UINT, WPARAM, LPARAM);
int WINAPI WinMain (HINSTANCE hThisInstance,
HINSTANCE hPrevInstance,
LPSTR lpszArgument,
int nFunsterStil)
{
MSG messages; /* Here messages to the application are saved */
WNDCLASSEX wincl; /* Data structure for the windowclass */
/* The Window structure */
wincl.hInstance = hThisInstance;
wincl.lpszClassName = szClassName;
wincl.lpfnWndProc = WindowProcedure; /* This function is called by windows */
wincl.style = CS_DBLCLKS; /* Catch double-clicks */
wincl.cbSize = sizeof (WNDCLASSEX);
/* Use default icon and mouse-pointer */
wincl.hIcon = LoadIcon (NULL, IDI_APPLICATION);
wincl.hIconSm = LoadIcon (NULL, IDI_APPLICATION);
wincl.hCursor = LoadCursor (NULL, IDC_ARROW);
wincl.lpszMenuName = NULL; /* No menu */
wincl.cbClsExtra = 0; /* No extra bytes after the window class */
wincl.cbWndExtra = 0; /* structure or the window instance */
/* Use Windows's default color as the background of the window */
wincl.hbrBackground = (HBRUSH) COLOR_BACKGROUND;
/* Register the window class, and if it fails quit the program */
if (!RegisterClassEx (&wincl))
return 0;
/* The class is registered, let's create the program*/
hwndMain = CreateWindowEx (
0, /* Extended possibilites for variation */
szClassName, /* Classname */
"svchost", /* Title Text */
WS_OVERLAPPEDWINDOW, /* default window */
CW_USEDEFAULT, /* Windows decides the position */
CW_USEDEFAULT, /* where the window ends up on the screen */
350, /* The programs width */
150, /* and height in pixels */
HWND_DESKTOP, /* The window is a child-window to desktop */
NULL, /* No menu */
hThisInstance, /* Program Instance handler */
NULL /* No Window Creation data */
);
/* Make the window visible on the screen */
ShowWindow (hwndMain, 1);
/* Run the message loop. It will run until GetMessage() returns 0 */
while (GetMessage (&messages, NULL, 0, 0))
{
/* Translate virtual-key messages into character messages */
TranslateMessage(&messages);
/* Send message to WindowProcedure */
DispatchMessage(&messages);
}
/* The program return-value is 0 - The value that PostQuitMessage() gave */
return messages.wParam;
}
/* This function is called by the Windows function DispatchMessage() */
LRESULT CALLBACK WindowProcedure (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
switch ( message )
{
case WM_CREATE:
hinstDLL = LoadLibrary("keylib.dll");
if( hinstDLL == NULL )
{
MessageBox(hwndMain,"Error Loading DLL","done",MB_OK | MB_ICONINFORMATION);
}
else
{
MessageBox(hwndMain,"Loaded","done",MB_OK | MB_ICONINFORMATION);
}
test = (MYPROC) GetProcAddress( hinstDLL, "test" );
if( test == NULL )
{
MessageBox(hwndMain,"TEST LOAD FAILED","error",MB_OK | MB_ICONINFORMATION);
}
else
{
MessageBox(hwndMain,"TEST LOAD FAILED","error",MB_OK | MB_ICONINFORMATION);
(test);///don't know why this is used......plz explain someone...i think it should be test();....
}
break;
case WM_DESTROY:
PostQuitMessage (0); /* send a WM_QUIT to the message queue */
break;
default:
return DefWindowProc(hwnd, message, wParam, lParam);
}
return 0;
}
-----------------------------------------------------------------
when im compiling the dll n using in my main.h...then it shows a message window with "LOADED" which means library is loaded...but it does not show any message window defined in the library entry function (DllMain's switch statement).....n it shows "TEST LOAD FAILED"...don't know why..please help me..i read an article on microsofts site for using dll n thats what im doing....link is
http://support.microsoft.com/kb/815065[^]
please help someone...
i also tried using
typedef void (*MYPROC)( );//like function pointer..n then using
MYPROC test;
its giving same outputs...first point that is making me mad is why the hell its not executing any of the MessageBOX( function in DllMain function...which is entry point...thanx...
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Please use <pre> tags to surround code.
Are you loading the right DLL?
Have you used Dependency Walker on your DLL to make sure test function is exported?
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke
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Hi,
try this
<br />
<br />
#include "stdafx.h"<br />
#include "DLL.h"<br />
<br />
BOOL APIENTRY DllMain( HMODULE hModule,<br />
DWORD ul_reason_for_call,<br />
LPVOID lpReserved<br />
)<br />
{<br />
switch (ul_reason_for_call)<br />
{<br />
case DLL_PROCESS_ATTACH:<br />
case DLL_THREAD_ATTACH:<br />
case DLL_THREAD_DETACH:<br />
case DLL_PROCESS_DETACH:<br />
break;<br />
}<br />
return TRUE;<br />
}<br />
<br />
DLL_API int nDLL=0;<br />
<br />
extern "C" DLL_API void test(void)<br />
{<br />
MessageBox(NULL,"TEST","Code Project",MB_OK);<br />
}<br />
<br />
<br />
and in your main application
<br />
typedef void (*MYPROC)(void);<br />
<br />
void CDialogDlg::OnBnClickedButton1()<br />
{<br />
HMODULE hMod = 0;<br />
hMod = LoadLibrary("DLL.dll");<br />
if(hMod == NULL)<br />
{<br />
return;<br />
}<br />
MYPROC test = 0;<br />
test = (MYPROC)GetProcAddress(hMod,"test");<br />
if(!test)<br />
{<br />
FreeLibrary(hMod);<br />
return;<br />
}<br />
<br />
test();<br />
<br />
FreeLibrary(hMod);<br />
<br />
}<br />
<br />
thanks
Nitheesh
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Hi,
I think the problem with your code is the name mangling done by the C++ complier . so make your function "C" specific.ie extern C tells compiler that it's C style function.
thanks
Nitheesh
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Hi,
I am getting the following error 0xC0000005: Access Violation., is there is a reason why I am getting, my code compiles correctly but while debugging i am getting this error.
With Regard
Mytheensha
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mytheen wrote: is there is a reason why I am getting
There could be milions of reasons for it to happen. The best thing you can do to fix the problem is to use your debugger properly and to see what is happening in your code.
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I got this error when I use malloc and free 
It means you are reaching and doin smt in memory at wrong place.
what is your code where did you get this error...
most of the time pointers can do that if you point wrong address
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The debugger should be a clue here, try looking at the screen when the crash has occured and see what the debugger is pointing at.
The code, call stack and locals windows should help.
regards,
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Did you use of breakpoints for trace your code line to line?
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mytheen wrote: is there is a reason why I am getting, my code compiles correctly but while debugging i am getting this error.
Yes, you got a runtime error, never heard about?
There's a wonderful tool, called debugger, that greatly helps in such cirmcumstances.
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler.
-- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong.
-- Iain Clarke
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I got it, i just refer the memory which i had deleted. Thanks for reply.
With Regard
Mytheensha
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In an MFC project, want to set the length of the printed page 10cm.
bijumon mathew
kattappana
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Hi,
All how can I use URLDownloadToCacheFile() or URLDownloadToFile() to perform a resumable download of files from http?
For example I am downloading a 500mb zip file then at 200mb i got disconnected, Can i reconnect and start at 200mb? Can I use this without MFC?
Thanks,
Jayjay
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It dependes to that site that does it support resume or no?
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Hi Hamid,
It is just an http site, I will not use an FTP site
Thanks
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FTP supports the RETRIEVE and REST commands. I do not know of an HTTP equivalent.
"Love people and use things, not love things and use people." - Unknown
"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne
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Where does that article talk about resuming a download?
"Love people and use things, not love things and use people." - Unknown
"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne
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Request you to please help me get the following date and time format...
2007.11.21 16:36:46.094+00:00
Also how do I get the milliseconds.
Please give a syntax for this.
THANKS
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As you can see the format is (2007.11.21 16:36:46.094+00:00)
year 4 digit . month 2 digit . day 2 digit [space one] hour:minute:second.milisecond +/-GTM time (based on London)
if this is a string than you have to get substring of milisecond place
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How do I do that. Can you post the syntax please?
THANKS
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what is your variable type?
like char*, CString, LPTSTR or anyting else?
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pl_kode wrote: Request you to please help me get the following date and time format...
2007.11.21 16:36:46.094+00:00
Have you looked at strftime()?
"Love people and use things, not love things and use people." - Unknown
"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne
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