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Q188897: HOWTO: Setting the System Date and Time Programmatically

Article: Q188897
Product(s): Microsoft FoxPro
Version(s): WINDOWS:5.0,5.0a
Operating System(s): 
Keyword(s): 
Last Modified: 30-JUL-1999

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, versions 5.0, 5.0a 
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SUMMARY
=======

Although the system date and time can be set manually from Control Panel,
programatically changing these settings requires using the Win32 SetLocalTime
function.

SetLocalTime is passed a SYSTEMTIME structure, containing the following members:

  WORD wYear
  WORD wMonth
  WORD wDayOfWeek
  WORD wDay
  WORD wHour
  WORD wMinute
  WORD wSecond
  WORD wMilliseconds

Similar to all structures, you must construct a string containing its proper
memory representation. The Word2Str function in the code below performs this
conversion.

Also, note that it is necessary to subtract 1 from the result of the FoxPro dow()
function to obtain the wDayOfWeek member. Win32 treats Sunday as day 0 (zero)
and Saturday as day 6, whereas dow() treats Sunday as day 1 and Saturday as day
7.

It is more convenient to use the SetLocalTime function rather than the
intuitively more obvious choice, SetSystemTime, because the former treats the
SYSTEMTIME structure as a timezone-adjusted local time, while the latter
function treats the SYSTEMTIME structure as Greenwich Mean Time.

MORE INFORMATION
================

Create and execute a program containing the code below. The program stores the
current system date and time, changes it to 10:30:15.00 AM on 06/30/2001,
displays the FoxPro time() and date() functions to demonstrate that the date and
time have been changed, then resets them to their previous values.

Sample Code
-----------

     SET CENTURY ON

     * Save the current date and time, reset it at the end.
     m.olddate = DATE()
     m.oldtime = TIME(1)

     * Set the system time arbitrarily to 10:30:15 AM on 06/30/2001.
     m.updtdate = {06/30/2001}
     m.updttime = "10:30:15.00"
     =setsystime(m.updtdate, m.updttime)

     =MESSAGEBOX("Old date: " + DTOC(m.olddate) + CHR(13) + ;
        "Old time: " + m.oldtime + CHR(13) + ;
        "New system date: " + DTOC(DATE()) + CHR(13) + ;
        "New system time: " + TIME(1), ;
        0 + 64 + 0, ;
        "SetLocalTime()")

     * Now, reset it to its original value.
     m.updtdate = m.olddate
     m.updttime = m.oldtime
     =setsystime(m.updtdate, m.updttime)

     * Function setsystime.
     * Parameters: date, character time in the form HH:MM:SS:hh.
     * Returns: nothing.
     FUNCTION setsystime

     PARAMETERS m.updtdate, m.updttime

     DECLARE SHORT SetLocalTime IN win32api STRING SystemTime

     * Use SendMessage to tell everybody that we've changed the system time.
     DECLARE INTEGER SendMessage IN win32api ;
        INTEGER WindowHandle, ;
        INTEGER MESSAGE, ;
        STRING Param1, ;
        STRING Param2

     * SendMessage constants.
     #DEFINE HWND_BROADCAST 65535
     #DEFINE WM_TIMECHANGE 30

     m.SystemTime = word2str(YEAR(m.updtdate)) + ;
        word2str(MONTH(m.updtdate)) + ;
        word2str(DOW(m.updtdate) - 1) + ;
        word2str(DAY(m.updtdate)) + ;
        word2str(VAL(LEFT(m.updttime, 2))) + ;
        word2str(VAL(SUBSTR(m.updttime, 4, 2))) + ;
        word2str(VAL(SUBSTR(m.updttime, 7, 2))) + ;
        word2str(VAL(RIGHT(m.updttime, 2)))

     m.retval = SetLocalTime(m.SystemTime)

     * Send the message that the time has changed.
     m.retval = SendMessage(HWND_BROADCAST, WM_TIMECHANGE, "", "")

     * Function word2str.
     * Parameters: 16-bit value.
     * Returns: low-high format string for use in structures
     * requiring a WORD value.
     FUNCTION word2str

     PARAMETERS m.wordval

     PRIVATE i, m.retstr

     m.retstr = ""
     FOR i = 8 TO 0 STEP -8
        m.retstr = CHR(INT(m.wordval/(2^i))) + m.retstr
        m.wordval = MOD(m.wordval, (2^i))
     NEXT
     RETURN m.retstr

REFERENCES
==========

The Win32 API help file included in the MSDN Platform SDK CD.

Additional query words: kbDSupport SYSTEMTIME SETLOCALTIME SETSYSTEMTIME time date kbDSE kbvfp500

======================================================================
Keywords          :  
Technology        : kbVFPsearch kbAudDeveloper kbVFP500 kbVFP500a
Version           : WINDOWS:5.0,5.0a
Issue type        : kbhowto

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