Managed C++/CLI

#include <Windows.h>
#include <strsafe.h>

ATOM RegisterMyClass(HINSTANCE, wchar_t*);
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
void ErrorExit(LPTSTR lpszFunction);

int WINAPI WinMain(HINSTANCE hInst, HINSTANCE hpInst, LPSTR cmd, int nCmdShow)
{
	HWND hwnd;
	MSG msg;
	wchar_t myWndClass[] = L"AWindow";
	wchar_t myWndTitle[] = L"My Window";

	RegisterMyClass(hInst, myWndClass);

	hwnd = CreateWindowW(myWndClass, myWndTitle, WS_OVERLAPPEDWINDOW,
			     10, 10, 300, 300, NULL, NULL, hInst, NULL);

	if ( hwnd == NULL )
		ErrorExit(L"CreateWindow");

	ShowWindow(hwnd, nCmdShow);
	UpdateWindow(hwnd);

	while ( GetMessage (&msg, NULL, 0, 0 ) )
	{
		TranslateMessage(&msg);
		DispatchMessage(&msg);
	}

	return 0;
}

ATOM RegisterMyClass(HINSTANCE hInst, wchar_t* wndClass)
{
	WNDCLASSEX w;
	
	w.cbSize = sizeof(WNDCLASSEX);
	w.style = CS_HREDRAW | CS_VREDRAW;
	w.lpfnWndProc = WndProc;
	w.cbClsExtra = 0;
	w.cbWndExtra = 0;
	w.hInstance = hInst;
	w.hIcon = LoadIcon(NULL, IDI_APPLICATION);
	w.hCursor = LoadCursor(NULL, IDC_ARROW);
	w.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
	w.lpszMenuName = NULL;
	w.lpszClassName = wndClass;
	w.hIconSm = NULL;

	return RegisterClassEx(&w);
}

LRESULT CALLBACK WndProc(HWND hWnd, UINT msg, WPARAM wp, LPARAM lp)
{
	HDC hdc;
	PAINTSTRUCT ps;

	switch (msg)
	{
	case WM_CREATE:
		break;
	case WM_PAINT:
		hdc = BeginPaint(hWnd, &ps);
		EndPaint(hWnd, &ps);
		break;
	case WM_DESTROY:
		PostQuitMessage(0);
		break;
	default:
		DefWindowProc(hWnd, msg, wp, lp);
	}
	return 0;
}

void ErrorExit(LPTSTR lpszFunction) 
{ 
    // Retrieve the system error message for the last-error code

    LPVOID lpMsgBuf;
    LPVOID lpDisplayBuf;
    DWORD dw = GetLastError(); 

    FormatMessage(
        FORMAT_MESSAGE_ALLOCATE_BUFFER | 
        FORMAT_MESSAGE_FROM_SYSTEM |
        FORMAT_MESSAGE_IGNORE_INSERTS,
        NULL,
        dw,
        MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
        (LPTSTR) &lpMsgBuf,
        0, NULL );

    // Display the error message and exit the process

    lpDisplayBuf = (LPVOID)LocalAlloc(LMEM_ZEROINIT, 
        (lstrlen((LPCTSTR)lpMsgBuf) + lstrlen((LPCTSTR)lpszFunction) + 40) * sizeof(TCHAR)); 
    StringCchPrintf((LPTSTR)lpDisplayBuf, 
        LocalSize(lpDisplayBuf) / sizeof(TCHAR),
        TEXT("%s failed with error %d: %s"), 
        lpszFunction, dw, lpMsgBuf); 
    MessageBox(NULL, (LPCTSTR)lpDisplayBuf, TEXT("Error"), MB_OK); 

    LocalFree(lpMsgBuf);
    LocalFree(lpDisplayBuf);
    ExitProcess(dw); 
}

private: public: System::Void button2_Click(System::Object^  sender, System::EventArgs^  e) {	
	Random^ gen=gcnew Random;
	serialPort1->Write(Convert::ToString(gen->Next(0,100)+"P"));
}

public: System::Void serialPort1_DataReceived(System::Object^  sender, System::IO::Ports::SerialDataReceivedEventArgs^  e) {	 
		String^ st = serialPort1->ReadExisting();
		button1->Text=st;
		}