SendMessage from modaless dialog to the view in SDI without document/view structure support

I create one SDI without document/view structure support, i name the project as ImagePro, then I can get the following files:

ChildView.cpp; (class CChildView : public CWnd， OnPaint() is here)
MainFrm.cpp; (class CMainFrame : public CFrameWnd)
ImagePro.cpp;(class CImageProApp : public CWinApp)

I also create CModalLessDlg using the dialog template, which is defined in ModalLessDlg.cpp and ModalLessDlg.h

In the  ModalLessDlg.cpp, I want to press the "Begin" button to send a text to the "view"

you can realize it like this:

1. in MainFrm.h, there is one protected variable:

protected: CChildView   m_wndView;

change it as public variable:

public: CChildView   m_wndView;

2. in ModalLessDlg.cpp:

#define WM_MY_DOSOME (WM_USER+1)

3. in ModalLessDlg.cpp:

void CModalLessDlg::OnBegin() // 
{
 // TODO: start
    
  CMainFrame   *pFrame=(CMainFrame*)(AfxGetApp()->m_pMainWnd); 
  char buf[]="I LOVE YOU";
 (pFrame->m_wndView).SendMessage(WM_MY_DOSOME,(WPARAM)buf,0);

}

4. In ChildView.h, add the following:

afx_msg LRESULT OnMyMessage(WPARAM wParam, LPARAM lParam);//before DECLARE_MESSAGE_MAP()

5. in ChildView.cpp, add the following:

BEGIN_MESSAGE_MAP(CChildView, CWnd)
 // ...
    ON_MESSAGE(WM_MY_DOSOME,OnMyMessage)  //only need to add this line

 //...
END_MESSAGE_MAP()

//then realize the response function:

LRESULT CChildView::OnMyMessage(WPARAM iParam1,LPARAM iParam2)
{
   
 char *buf=(char *)iParam1; 
 CString str;
 str.Format("%s",buf);
 MessageBox(str);
 return 0L;

}

the function is only a test to see whether you can receive the text or not, you can also show it in the client area of the view through Invalidate() again in this OnMyMessage function.