Visual C++ Linking with mmsystem.h

koooee · 07-02-2009, 09:49 AM

Hello I am trying to write a simple sound recorder in a win32 forms application using visual c++ and am having problems linking to mmsystem.h I have the recorder working fine in a console application but cannot get it to work as a win32 app. when trying to reference the function waveInGetNumDevs() I get a linking error when trying to compile:

Error 1 error LNK2028: unresolved token (0A000031) "extern "C" unsigned int __stdcall waveInGetNumDevs(void)" (?waveInGetNumDevs@@$$J10YGIXZ) referenced in function "public: __clrcall record::Form1::Form1(void)" (??0Form1@record@@$$FQ$AAM@XZ) record.objrecord

I am assuming this has to do with managed and unmanaged code mixed together. So i made a header file referencing just the needed function and surrounded it with #pragma unmanaged and am compiling with /clr option.

Here is the header file:

Code:

#sound.h
#include "windows.h"
#include "mmsystem.h"
#pragma unmanaged
WINMMAPI  UINT WINAPI waveInGetNumDevs(void);

Here is the code generating the error:

Code:

#include "sound.h"
#pragma managed
namespace record {

	using namespace System;
	using namespace System::ComponentModel;
	using namespace System::Collections;
	using namespace System::Windows::Forms;
	using namespace System::Data;
	using namespace System::Drawing;

	public ref class Form1 : public System::Windows::Forms::Form
	{
		HWAVEIN hwin;
		MMRESULT result;
		int numDevices;
	public:
		Form1(void)
		{
			InitializeComponent();
			numDevices = waveInGetNumDevs();
		}

Any help on this matter would be appreciated. Thanks a lot.

--koooee

hk_mp5kpdw · 07-02-2009, 02:11 PM

mmsystem.h is a header and you don't link with headers, you link with libraries. There is probably a library you need to explicitly link with (winmm.lib if I'm not mistaken) in your project settings.

koooee · 07-02-2009, 02:43 PM

i feel stupid....(that was in my console version of the code) thanks for the reply.

if anyone is wondering...put this line in stdafx.h

Code:

#pragma comment(lib, "winmm.lib")

07-02-2009, 09:49 AM	#1
koooee Registered User Join Date: Feb 2009 Posts: 8	Visual C++ Linking with mmsystem.h Hello I am trying to write a simple sound recorder in a win32 forms application using visual c++ and am having problems linking to mmsystem.h I have the recorder working fine in a console application but cannot get it to work as a win32 app. when trying to reference the function waveInGetNumDevs() I get a linking error when trying to compile: Error 1 error LNK2028: unresolved token (0A000031) "extern "C" unsigned int __stdcall waveInGetNumDevs(void)" (?waveInGetNumDevs@@$$J10YGIXZ) referenced in function "public: __clrcall record::Form1::Form1(void)" (??0Form1@record@@$$FQ$AAM@XZ) record.objrecord I am assuming this has to do with managed and unmanaged code mixed together. So i made a header file referencing just the needed function and surrounded it with #pragma unmanaged and am compiling with /clr option. Here is the header file: Code: #sound.h #include "windows.h" #include "mmsystem.h" #pragma unmanaged WINMMAPI UINT WINAPI waveInGetNumDevs(void); Here is the code generating the error: Code: #include "sound.h" #pragma managed namespace record { using namespace System; using namespace System::ComponentModel; using namespace System::Collections; using namespace System::Windows::Forms; using namespace System::Data; using namespace System::Drawing; public ref class Form1 : public System::Windows::Forms::Form { HWAVEIN hwin; MMRESULT result; int numDevices; public: Form1(void) { InitializeComponent(); numDevices = waveInGetNumDevs(); } Any help on this matter would be appreciated. Thanks a lot. --koooee
koooee is offline

07-02-2009, 02:11 PM	#2
hk_mp5kpdw Registered User Join Date: Jan 2002 Location: Northern Virginia/Washington DC Metropolitan Area Posts: 2,787	mmsystem.h is a header and you don't link with headers, you link with libraries. There is probably a library you need to explicitly link with (winmm.lib if I'm not mistaken) in your project settings. __________________ On two occasions I have been asked [by members of Parliament], 'Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?' I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question. --Charles Babbage, 1792-1871 09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0
hk_mp5kpdw is offline

07-02-2009, 02:43 PM	#3
koooee Registered User Join Date: Feb 2009 Posts: 8	i feel stupid....(that was in my console version of the code) thanks for the reply. if anyone is wondering...put this line in stdafx.h Code: #pragma comment(lib, "winmm.lib")
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