Creating DLL in DevC++

**kkchennai** · 03-13-2006

I have a long .C file full of functions.Now I want to group those functions and create them as a dll. I am working in DevC++.
So please help me to create dll in DevC++ and also to access the dll in another DevC++ console application.
Please help me............

**NogginTheNog** · 03-13-2006

open dev-cpp
File-->New Project
choose DLL and 'c or c++'
click OK

click Save in save dialog

add an include to your source file

before you exportable functions (& their prototypes) add "__declspec (dllexport)"
like
__declspec (dllexport) DWORD ud (void){return updated;}

Off you go ! you can change the executable produced (the .dll) in project properties

I don't know how to do 'import libraries', you can call the exported funcs from an exe like this:

Code:

typedef DWORD (* LPFNDLL_hp2) (DWORD *d );
LPFNDLL_hp2 lpfn_hp2;
HINSTANCE Hdllhp;

//get dll func address
Hdllhp = LoadLibrary("your_DLL_name.dll");
		if(!Hdllhp){
			ssmsg("Missing DLL: your_DLL_name.dll");return FALSE;
		}

lpfn_hp2 = (LPFNDLL_hp)GetProcAddress(Hdllhp , "dw");

//call func in DLL
(lpfn_hp2)(0x1234abcd);

I use this extensively calling DLL funcs from DLLs produced in both Dev-C++ and Borland 5.5,
called from an EXE made with Borland, or another in assembler.

when you create the dll project, dev-cpp will create these lines

Code:

#if BUILDING_DLL
# define DLLIMPORT __declspec (dllexport)
#else /* Not BUILDING_DLL */
# define DLLIMPORT __declspec (dllimport)
#endif /* Not BUILDING_DLL */

you just define BUILDING_DLL for your dll and not for the app that calls the functions, so

Code:

__declspec (dllexport) DWORD ud (void){return updated;}

becomes

Code:

DLLIMPORT DWORD ud (void){return updated;}

Note the DWORD above is the return type, and this example has no params, i.e.void. 'updated' was just a global from where I copy/pasted from.

Hope this helps...........

**kkchennai** · 03-13-2006

hi,
thanks for ur reply...but stiil i am not able to access the dll functions.........
This is my dll.h file:

Code:

     #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 HelloWorld (void);


#endif /* _DLL_H_ */

this is my dllmain.c file

Code:

#include "dll.h"
#include <windows.h>
#include <stdio.h>
#include <stdlib.h>

DLLIMPORT void HelloWorld ()
{
    printf("\n hai");
}


BOOL APIENTRY DllMain (HINSTANCE hInst     /* Library instance handle. */ ,
                       DWORD reason        /* Reason this function is being called. */ ,
                       LPVOID reserved     /* Not used. */ )
{
    switch (reason)
    {
      case DLL_PROCESS_ATTACH:
        break;

      case DLL_PROCESS_DETACH:
        break;

      case DLL_THREAD_ATTACH:
        break;

      case DLL_THREAD_DETACH:
        break;
    }

    /* Returns TRUE on success, FALSE on failure */
    return TRUE;
}

I am able to compile my dll without any erros.

This is my .c file in which i invoke the dll:

Code:

#include <stdio.h>
#include <windows.h>
#include <stdlib.h>
#include "dll.h"

int main(int argc, char *argv[])
{
  HelloWorld();
  system("PAUSE");	
  return 0;
}

when i compile this .c file i get a compile time error in the makefile.win...this is the exact error:

C:\Dev-Cpp\test4\Makefile.win [Build Error] [test4.exe] Error 1

Please help me out...Should i change any of the project settings while accessing the dll?

**NogginTheNog** · 03-14-2006

The .c file knows the name and signature(return type & params) of your function, but hasnt loaded the dll yet. Read back in my earlier post about = LoadLibrary("your_DLL_name.dll"); and GetProcAddress(Hdllhp , "dll_function");

if you have a test func in the dll like
void Hello(void)
add a call to MessageBox() in it
then you can test the func like this from the command line

rundll32 MyDll.dll,Hello

**NogginTheNog** · 03-14-2006

If you get the free command-line Borland 5.5 compiler package, it includes a utility call tdump
This will display info about exe's and dll's, including exported names
start here
http://community.borland.com/cgi-bin...vey.cgi?sid=33

**dwks** · 03-15-2006

Or you can use QuickView (Windows) or ld or file (Linux) or a dependency viewer.

**kkchennai** · 03-17-2006

Hi thanks for ur reply..........
I used the APIs "LoadLibrary" to load the dll and "GetProcAddress " to load the functions , and it worked.........

thanks a lot..................

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