C / C++ / MFC

CPallini wrote:

I disagree. A window handle is unique on the system. You can post messages to the window whose that handle is assigned. At the end PostMessage is an IPC mechanism.

CPallini wrote:

BTW handles technically are not memory addresses.

typedef void* HANDLE;

Maxwell Chen wrote:

There is a translation mechanism.

Maxwell Chen wrote:

The type void* is memory address.

CPallini wrote:

The type void* is a number that may contain a memory address.

CPallini wrote:

Since the window handle of a particular window is the same on different process (this, for instance, allows you to use in your application the handle found with Spy++ tool) and the processes have different address spaces, then window handles cannot be valid memory pointers in the context of such processes (at least IMHO ).

// Process A.
struct MyBlock
{
  int a;
};
void main()
{
  MyBlock* p = new MyBlock; // p = 0x00A30210
  p->a = 3;
  // No delete to let it being kept.
}
// Process B.
struct MyBlock
{
  int a;
};
void main()
{
  void* p = reinterpret_cast<void*>(0x00A30210);
  cout << reinterpret_cast<myblock*>(p)->a;
}

Maxwell Chen wrote:

I am not sure, but if it is just a number, a ULONG is just fine. Since it is defined as a pointer type (void*), it must be some address pointing to something.

typedef  ULONG  HANDLE;

Maxwell Chen wrote:

I am not sure, but if it is just a number, a ULONG is just fine. Since it is defined as a pointer type (void*), it must be some address pointing to something.

Maxwell Chen wrote:

I guess that creating handle and free handle are something related with global allocating memory blocks in the heap

Hamid. wrote:

You can use of EnumWindows instead FindWindow

ashtwin. wrote:

Can anybody tell is that correct or any problem in using the handle of a window in one process from some other process.

ashtwin wrote:

Currently i am using FindWindow() to get the handle of a dialog and using that handle i am sending the message(using PostMessage api)to this dialog(which is part of seperate process). As of now it is working fine.

ashtwin wrote:

Hi, i am using FindWindow() function to get the handle of a dialog in one process from some other process. Can anybody tell is that correct or any problem...

#include "stdafx.h"<br />
#include <winsock2.h><br />
#include <windows.h><br />
#include <iostream><br />
#include <mmsystem.h><br />
#pragma comment(lib, "ws2_32.lib")<br />
#pragma comment(lib, "Winmm.lib")<br />
using namespace System;<br />
using namespace std;<br />
static void CALLBACK WaveInProc(HWAVEIN, UINT,  DWORD , DWORD , DWORD );<br />
<br />
static const int SNDNBUF = 2;<br />
static const int SNDSIZEBUF = 320;<br />
HWAVEOUT hWavout;<br />
MMRESULT mmrr;<br />
WAVEHDR headersend[SNDNBUF];<br />
char hdrDatasend[SNDSIZEBUF*SNDNBUF];<br />
HWAVEIN hWavin;<br />
<br />
int _tmain(int argc, _TCHAR* argv[])<br />
{<br />
			WAVEFORMATEX wfx; <br />
			 wfx.nSamplesPerSec = 8000;<br />
			 wfx.nChannels = 1;<br />
			 wfx.wFormatTag = WAVE_FORMAT_PCM;<br />
			 wfx.wBitsPerSample = 16;<br />
			 wfx.nBlockAlign = wfx.nChannels * (wfx.wBitsPerSample / 8);<br />
			 wfx.nAvgBytesPerSec = wfx.nSamplesPerSec * wfx.nBlockAlign;<br />
<br />
	memset(headersend, 0,sizeof(WAVEHDR)*SNDNBUF);<br />
			 for(int i=0;i<sndnbuf;i++){<br />
				 headersend[i].lpData = hdrDatasend + i*SNDSIZEBUF;<br />
 				 headersend[i].dwBufferLength =  SNDSIZEBUF;}<br />
<br />
			  memset(hdrDatasend,0,SNDSIZEBUF*SNDNBUF);<br />
			<br />
			if(waveInOpen(&hWavin,WAVE_MAPPER, &wfx,(DWORD_PTR)WaveInProc ,0,  CALLBACK_FUNCTION) == MMSYSERR_NOERROR){<br />
 				for(int i=0;i<sndnbuf;i++)>{  <br />
				   mmrr = waveInPrepareHeader(hWavin, headersend + i, sizeof(WAVEHDR));<br />
				   mmrr = waveInAddBuffer(hWavin, headersend + i, sizeof(WAVEHDR));}<br />
				mmrr = waveInStart(hWavin);	}<br />
			int i;<br />
			cin >> i;<br />
			mmrr=waveInStop(hWavin);<br />
			mmrr=waveInReset(hWavin);<br />
			Sleep(500);<br />
			for(int i=0;i<sndnbuf;i++){<br />
				if ((headersend+i)->dwFlags & WHDR_PREPARED){<br />
			mmrr=waveInUnprepareHeader(hWavin,headersend+i, sizeof(WAVEHDR));}<br />
			Sleep(500);<br />
mmrr=waveInClose(hWavin);<br />
				cin >> i;<br />
	return 0;<br />
}<br />
<br />
static void CALLBACK WaveInProc(HWAVEIN hw, UINT uMsg,DWORD_PTR dwInstance, DWORD_PTR dwParam1, DWORD dwParam2)<br />
{<br />
		 WAVEHDR* curhdrin = (WAVEHDR*)dwParam1;<br />
		if(uMsg != WIM_DATA)return;<br />
		waveInAddBuffer(hw, curhdrin, sizeof(WAVEHDR));<br />
		return;<br />
}</sndnbuf;i++)></mmsystem.h></iostream></windows.h></winsock2.h>