Example : User Message

stdafx.h

#define WM_USER_EXAMPLE (WM_USER + 10)

MainFrm.h

protected:
	afx_msg int OnCreate(LPCREATESTRUCT lpCreateStruct);
	afx_msg LONG OnUserExample(WPARAM wParam, LPARAM lParam);
	DECLARE_MESSAGE_MAP()

MainFrm.cpp

BEGIN_MESSAGE_MAP(CMainFrame, CFrameWnd)
	ON_WM_CREATE()
	ON_COMMAND(ID_MSG_SEND, OnMsgSend)
	ON_MESSAGE(WM_USER_EXAMPLE, OnUserExample)
END_MESSAGE_MAP()
 
 
void CMainFrame::OnMsgSend()
{
	SendMessage(WM_USER_EXAMPLE, (WPARAM)3.0);
}
 
LONG CMainFrame::OnUserExample(WPARAM wParam, LPARAM lParam)
{
	CString strMessage;
	int nNumber = (int)wParam;
 
	strMessage.Format("I received %d", nNumber);
	AfxMessageBox(strMessage, MB_OK | MB_ICONINFORMATION);
 
	return 0;
}