using multiple dlls

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May 19th, 2003, 05:29 PM

Combat

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using multiple dlls

i need to use multiple dlls, they dont have to intercommunicate. any body know how to get my executable to use them?

May 19th, 2003, 08:53 PM

Combat

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Doesnt anybody know this?

May 19th, 2003, 11:40 PM

Scorpions4ever

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What development environment are you using? Visual C++ or Borland C++. Also, are these Active-X DLLs or plain old DLLs?

May 20th, 2003, 02:00 AM

Combat

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sorry i wasnt clearer before, im using Dev-C++ and just plain old dlls will do fine.

May 20th, 2003, 04:54 AM

TechNoFear

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implicit (at run, easiest but whole app will fail if DLL not found) or explicit (as needed) linking?

Look at LoadLibrary(), GetProcAddress()

here is a quick example to explicitly load the function TrackMouseEvent() from the user32.dll

Code:

//define a funtion type
typedef BOOL (CALLBACK * TEST)(LPTRACKMOUSEEVENT);
//declare an instance of this function type
TEST				Test_TrackMouseEvent;
//DLL handle
HANDLE   hTME=NULL:

//ensue we are where the DLL will be found
SetCurrentDirectory(szDLLInThisDirectory);
//load up the DLL
hTME=LoadLibrary(".\\user32.dll");
if (hTME!=NULL)
{
//get the function we want and lock to our function pointer	
Test_TrackMouseEvent=(TEST)GetProcAddress(hTME,"TrackMouseEvent");

//error check
if(Test_TrackMouseEvent==NULL)
{
	iError=GetLastError();
}
//use if no error


//free library after use
FreeLibrary(hTME);

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May 20th, 2003, 01:06 PM

Combat

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wow, thanks so much!

June 1st, 2003, 05:26 PM

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Well i tried this now and i had a few problems. I fixed a typo and got rid of iError. Now ANSI C++ is causing me some problems. I get two Errors:

ANSI C++ forbids implicit conversion from `void *' in argument passing

ANSI C++ forbids implicit conversion from `void *' in argument passing

One points to this:

Code:

hTME=LoadLibrary(".\\user32.dll");

and this:

Code:

FreeLibrary(hTME);

Does anybody have any idea of how to fix this? remember i am using Dev-C++.

June 1st, 2003, 11:09 PM

Combat

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Doesn't anybody know how to make this ANSI compliant???

June 2nd, 2003, 11:47 AM

infamous41md

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well i've never used Dev-C++ but if i got that error i would try casting those arguments to (void *).

#10

June 2nd, 2003, 06:28 PM

Combat

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i found out what the problem was:
it doesnt like HANDLE hTME=NULL;

i got rid of hTME and only check if it loads the function (close enough) but now it doesnt load the dll. oh, i also got rid of SetCurrentDirectory(szDLLInThisDirectory);
szDLLInThisDirectory was undefined, i didnt feel like defining it and i dont think it really needs it.

Is there something i need to do different in the dll to make it load that function?

#11

June 2nd, 2003, 09:15 PM

TechNoFear

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The dangers of using code you do not understand.............Each line has a specific and at times essential purpose.

SetCurrentDirectory(szDLLInThisDirectory);

Ensures you are in the folder the DLL is in. I use GetCurrentDirectory() to 'fill in' szDLLInThisFolder as the app starts and keep as a global. I included it to show you that you must set the full path or set the app to look in the folder containing the DLL.

hTME=LoadLibrary(".\\user32.dll");

This actually loads the DLL. Without it you can't lock the functions down with GetProcAddress()

I seem to have led you astray. hTME should have been a HMODULE not a HANDLE (but HANDLE will work).

If you still get the error try a cast back to the type you want ie HMODULE
HINSTANCE will also work as HMODULE is a #define of HINSTANCE.

hTME = (HMODULE)LoadLibrary( ".\\user32.dll" );

or

hTME = (HANDLE)LoadLibrary( ".\\user32.dll" );

FreeLibrary(hTME);

is also essential as it frees the memory and resoucres associated with the DLL.

using multiple dlls

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