win api programming

[sde]

i know how to import a windows dll in c#, but i haven't done much c++ programming.

i want to use winmm to access midi function.

in c#, i would do this:

[DllImport("winmm.dll")] 
public static extern int midiOutOpen(ref int lphMidiOut, int uDeviceID, int dwCallback, int dwInstance, int dwFlags)

what is the equivalent in c++?

[joe_bruin]

two ways. you can link implicitly, by adding it to the linker parameters of your project. this is the easiest way (and generally what is done with all library dlls). or you can link explicitly by calling LoadLibrary(), linking your functions manually using GetProcAddress(), and releasing the dll with FreeLibrary().

in unix, you would use dlopen() for explicit linking.

[sde]

thanks joe.

#include <MMSystem.h>

that did it. now i just got to find out why i get all these 'undefined identifier' compiler errors when i include this library width c++.

[sde]

windows programming .. ugggh .. i'm not even sure if i'm approaching this right.

so far, i have been able to import mmsystem, and load the winmm dll, but i'm not sure how to call this: http://msdn.microsoft.com/library/de...getnumdevs.asp

it is supposed to return the number of midi inputs you have.

how would you call that function? here is what i have so far to load the library:

#include "stdafx.h"
#include "windows.h"
#include "mmsystem.h"

int _tmain(int argc, _TCHAR* argv[])
{
	HINSTANCE hLib=LoadLibrary("winmm.dll");

	if(hLib == NULL)
	{
		std::cout << "hLib is NULL";
		getchar();
		return 0;
	}

	unsigned long   iNumDevs, i;

	// here i want to call midiInGetNumDevs()
	// and assign it to iNumDevs


  FreeLibrary((HMODULE)hLib);
  getchar();
	
	return 0;
}

does it even look like i'm on the right track?

[joe_bruin]

there's no real point to doing this. just add winmm.dll to your linker parameters (should be somewhere in your project settings), and you will not have to jump any hoops to call your function.

if you want to use explicit loading, you should not include mmsystem.h. the functions prototypes in it would be useless, since the linker can't link against the library (in explicit loading, you are the linker).

[sde]

YES! Thanks again Joe! =)

#include "stdafx.h"
#include "windows.h"

int _tmain(int argc, _TCHAR* argv[])
{
	unsigned long   iNumDevs,oNumDevs;

	iNumDevs = midiInGetNumDevs();
	oNumDevs = midiOutGetNumDevs();

	std::cout << "You Have " << iNumDevs << " MIDI Input Device(s)\n";
	std::cout << "and " << oNumDevs << " MIDI Output Device(s).";

  getchar();	
	return 0;
}

Output:

You Have 2 MIDI Input Device(s)
and 7 MIDI Output Device(s).

[Redline]

Out of curiosity Mike, which compiler were you using for this? I'm starting to read up on C, and have had issues including various windows.h's in my compiler of choice, Borland turbo. I have a trial version of visual c++, but that seems to just be complicating things for me