As opposed to the time set on a computer, a timer is partly but greatly under your control. Users do not see nor use a timer as a control. As a programmer, you decide if, why, when, and how to use this control.

1. Start Microsoft Visual Studio
2. To create a new application, on the main menu, click File -> New Project...
3. In the middle list, click MFC Application and set the name to CurrentTime1
4. Click OK
5. In the first page of the wizard, click Next
6. In the second page of the wizard, click Dialog based and click Next
7. In the third page of the wizard, click Finish
8. On the dialog box, click the TODO label
9. In the Properties window, change the following characteristics:
   Caption: 00:00:00 AM
   ID: IDC_CURRENT_TIME
10. Click an unoccupied area of the dialog box
11. In the Properties window, click Font (Size) then click ellipsis button
12. In the Font box, select Times New Roman
13. In the Font Style, click Bold
14. In the Size box, click 24
15. Click OK
     
    
16. Right-click the 00:00:00 AM label and click Add Variable...
17. Set the Category to Value
18. Make sure the type is set to CString and set the name to m_CurrentTime
19. Click Finish

Unlike most other controls, the MFC timer has neither a button to represent it nor a class. To create a timer, you simply call the SetTimer() member function of the CWnd class. Its syntax is:

UINT SetTimer(UINT nIDEvent, UINT nElapse,
void (CALLBACK EXPORT* lpfnTimer)(HWND, UINT, UINT, DWORD));

This function call creates a timer for your application. Like the other controls, a timer uses an identifier. This is passed as the nIDEvent argument. As mentioned already, when it is accessed, a timer starts counting up to a set value. Once it reaches that value, it stops and starts counting again. The nElapse argument specifies the number of milliseconds that the timer must count before starting again. The lpfnTimer argument is the name of a procedure that handles the timing event of the control. This argument can be set to NULL, in which case the timing event would rest on the CWnd's responsibility.

1. In the Class View, expand the CurrentTime1 project and click CCurrentTime1Dlg
2. In the lower part of the Class View, double-click OnInitDialog
3. Change the event as follows:

   BOOL CCurrentTime1Dlg::OnInitDialog()
   {
       CDialogEx::OnInitDialog();
   
       // Add "About..." menu item to system menu.
   
       // IDM_ABOUTBOX must be in the system command range.
       ASSERT((IDM_ABOUTBOX & 0xFFF0) == IDM_ABOUTBOX);
       ASSERT(IDM_ABOUTBOX < 0xF000);
   
       CMenu* pSysMenu = GetSystemMenu(FALSE);
       if (pSysMenu != NULL)
       {
   	BOOL bNameValid;
   	CString strAboutMenu;
   	bNameValid = strAboutMenu.LoadString(IDS_ABOUTBOX);
   	ASSERT(bNameValid);
   	if (!strAboutMenu.IsEmpty())
   	{
   		pSysMenu->AppendMenu(MF_SEPARATOR);
   		pSysMenu->AppendMenu(MF_STRING, IDM_ABOUTBOX, strAboutMenu);
   	}
       }
   
       // Set the icon for this dialog.  The framework does this automatically
       //  when the application's main window is not a dialog
       SetIcon(m_hIcon, TRUE);			// Set big icon
       SetIcon(m_hIcon, FALSE);		// Set small icon
   
       // TODO: Add extra initialization here
       SetTimer(1, 200, 0);
   
       return TRUE;  // return TRUE  unless you set the focus to a control
   }

When a timer is accessed or made available, it starts counting. Once the nElapse value of the CWnd::SetTimer() member function is reached, its sends a WM_TIMER message to the application.

We saw that a timer is initiated with a call to SetTimer(). When you do not need the timer anymore, call the CWnd::KillTimer() member function. Its syntax is:

BOOL KillTimer(int nIDEvent);

The nIDEvent argument identifies the timer that was created with a previous call to SetTimer().