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Fast Track Visual C++ 6.0 Programming
Our program is complete. Run it now, as shown in Figure 9.2, and select the Find max and min item in the File menu. This launches the two threads, MaxThread and MinThread. MaxThread finds the maximum of the array and sets the event that MinThread waits for. MinThread then continues and finds the minimum of the array. The result appears in the view, as shown in Figure 9.2. Now were coordinating multiple threads, which is an important part of true multitasking. The code for this example, DoubleThreadsView.h and DoubleThreadsView.cpp, appears in Listing 9.2. Listing 9.2 DoubleThreadsView.h and DoubleThreadsView.cpp // DoubleThreadsView.h : interface of the CDoubleThreadsView class // ///////////////////////////////////////////////////////////////////////////// #if !defined(AFX_DOUBLETHREADSVIEW_H__A880E565_A6EB_11D1_887F_D42B07C10710__INCLUDED_) #define AFX_DOUBLETHREADSVIEW_H__A880E565_A6EB_11D1_887F_D42B07C10710__INCLUDED_ #if _MSC_VER > 1000 #pragma once #endif // _MSC_VER > 1000 UINT MaxThreadProcedure(LPVOID pParam); UINT MinThreadProcedure(LPVOID pParam); struct SData { int array[5]; int max; int min; HANDLE flag; HWND NotifyWindow; }; class CDoubleThreadsView : public CView { protected: // create from serialization only CDoubleThreadsView(); DECLARE_DYNCREATE(CDoubleThreadsView) // Attributes public: CDoubleThreadsDoc* GetDocument(); SData data; CWinThread* MaxThread; void OnMaxFound(WPARAM wParam, LPARAM lParam); CWinThread* MinThread; void OnMinFound(WPARAM wParam, LPARAM lParam); // Operations public: // Overrides // ClassWizard generated virtual function overrides //{{AFX_VIRTUAL(CDoubleThreadsView) public: virtual void OnDraw(CDC* pDC); // overridden to draw this view virtual BOOL PreCreateWindow(CREATESTRUCT& cs); protected: virtual BOOL OnPreparePrinting(CPrintInfo* pInfo); virtual void OnBeginPrinting(CDC* pDC, CPrintInfo* pInfo); virtual void OnEndPrinting(CDC* pDC, CPrintInfo* pInfo); //}}AFX_VIRTUAL // Implementation public: virtual ~CDoubleThreadsView(); #ifdef _DEBUG virtual void AssertValid() const; virtual void Dump(CDumpContext& dc) const; #endif protected: // Generated message map functions protected: //{{AFX_MSG(CDoubleThreadsView) afx_msg void OnFileFindmaxandmin(); //}}AFX_MSG DECLARE_MESSAGE_MAP() }; #ifndef _DEBUG // debug version in DoubleThreadsView.cpp inline CDoubleThreadsDoc* CDoubleThreadsView::GetDocument() { return (CDoubleThreadsDoc*)m_pDocument; } #endif ///////////////////////////////////////////////////////////////////////////// //{{AFX_INSERT_LOCATION}} // Microsoft Visual C++ will insert additional declarations immediately before the previous line. #endif //!defined(AFX_DOUBLETHREADSVIEW_H__A880E565_A6EB_11D1_887F_D42B07C10710__INCLUDED_) // DoubleThreadsView.cpp : implementation of the CDoubleThreadsView class // #include stdafx.h #include DoubleThreads.h #include DoubleThreadsDoc.h #include DoubleThreadsView.h #ifdef _DEBUG #define new DEBUG_NEW #undef THIS_FILE static char THIS_FILE[] = __FILE__; #endif ///////////////////////////////////////////////////////////////////////////// // CDoubleThreadsView IMPLEMENT_DYNCREATE(CDoubleThreadsView, CView) BEGIN_MESSAGE_MAP(CDoubleThreadsView, CView) //{{AFX_MSG_MAP(CDoubleThreadsView) ON_COMMAND(ID_FILE_FINDMAXANDMIN, OnFileFindmaxandmin) ON_MESSAGE(WM_MAX, OnMaxFound) ON_MESSAGE(WM_MIN, OnMinFound) //}}AFX_MSG_MAP // Standard printing commands ON_COMMAND(ID_FILE_PRINT, CView::OnFilePrint) ON_COMMAND(ID_FILE_PRINT_DIRECT, CView::OnFilePrint) ON_COMMAND(ID_FILE_PRINT_PREVIEW, CView::OnFilePrintPreview) END_MESSAGE_MAP() ///////////////////////////////////////////////////////////////////////////// // CDoubleThreadsView construction/destruction CDoubleThreadsView::CDoubleThreadsView() { data.flag = CreateEvent(NULL, FALSE, FALSE, NULL); } CDoubleThreadsView::~CDoubleThreadsView() { } BOOL CDoubleThreadsView::PreCreateWindow(CREATESTRUCT& cs) { // TODO: Modify the Window class or styles here by modifying // the CREATESTRUCT cs return CView::PreCreateWindow(cs); } ///////////////////////////////////////////////////////////////////////////// // CDoubleThreadsView drawing void CDoubleThreadsView::OnDraw(CDC* pDC) { CDoubleThreadsDoc* pDoc = GetDocument(); ASSERT_VALID(pDoc); pDC->TextOut(0, 0, pDoc->text); } ///////////////////////////////////////////////////////////////////////////// // CDoubleThreadsView printing BOOL CDoubleThreadsView::OnPreparePrinting(CPrintInfo* pInfo) { // default preparation return DoPreparePrinting(pInfo); } void CDoubleThreadsView::OnBeginPrinting(CDC* /*pDC*/, CPrintInfo* /*pInfo*/) { // TODO: add extra initialization before printing } void CDoubleThreadsView::OnEndPrinting(CDC* /*pDC*/, CPrintInfo* /*pInfo*/) { // TODO: add cleanup after printing } ///////////////////////////////////////////////////////////////////////////// // CDoubleThreadsView diagnostics #ifdef _DEBUG void CDoubleThreadsView::AssertValid() const { CView::AssertValid(); } void CDoubleThreadsView::Dump(CDumpContext& dc) const { CView::Dump(dc); } CDoubleThreadsDoc* CDoubleThreadsView::GetDocument() // non-debug version is inline { ASSERT(m_pDocument->IsKindOf(RUNTIME_CLASS(CDoubleThreadsDoc))); return (CDoubleThreadsDoc*)m_pDocument; } #endif //_DEBUG ///////////////////////////////////////////////////////////////////////////// // CDoubleThreadsView message handlers void CDoubleThreadsView::OnFileFindmaxandmin() { // TODO: Add your command handler code here data.array[0] = 0; data.array[1] = 1; data.array[2] = 2; data.array[3] = 3; data.array[4] = 4; data.max = 0; data.NotifyWindow = m_hWnd; MaxThread = AfxBeginThread(MaxThreadProcedure, &data); ResetEvent(data.flag); MinThread = AfxBeginThread(MinThreadProcedure, &data); } UINT MaxThreadProcedure(LPVOID pParam) { SData* pData = (SData*)pParam; for(int loop_index = 0; loop_index <= 4; loop_index++){ if(pData->array[loop_index] > pData->max) pData->max = pData->array[loop_index]; } ::PostMessage(pData->NotifyWindow, WM_MAX, 0, 0); SetEvent(pData->flag); return 0; } UINT MinThreadProcedure(LPVOID pParam) { SData* pData = (SData*)pParam; WaitForSingleObject(pData->flag, INFINITE); pData->min = pData->max; for(int loop_index = 0; loop_index <= 4; loop_index++){ if(pData->array[loop_index] < pData->min) pData->min = pData->array[loop_index]; } ::PostMessage(pData->NotifyWindow, WM_MIN, 0, 0); return 0; } void CDoubleThreadsView::OnMaxFound(WPARAM wParam, LPARAM lParam) { CDoubleThreadsDoc* pDoc = GetDocument(); ASSERT_VALID(pDoc); char FormattedString[100]; wsprintf(FormattedString, Maximum value in array = %d, , data.max); pDoc->text = FormattedString; TerminateThread(MaxThread, 0); Invalidate(); } void CDoubleThreadsView::OnMinFound(WPARAM wParam, LPARAM lParam) { CDoubleThreadsDoc* pDoc = GetDocument(); ASSERT_VALID(pDoc); char FormattedString[100]; wsprintf(FormattedString, minimum value in array = %d , data.min); pDoc->text += FormattedString; TerminateThread(MinThread, 0); Invalidate(); } Whats AheadIn the next chapter, we begin exploring an exceptionally powerful aspect of working with Windows: Dynamic Link Libraries (DLLs). Just about all Windows users have seen DLLs, and in the next chapter, we see how they can be useful to us and how to create them.
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