How To Determine When a 32-bit Process has Completed

MORE INFORMATION

Step-by-Step Example

1. Create a program from the following code (the path to Notepad.exe may need to be modified to reflect your system configuration):

         #DEFINE NORMAL_PRIORITY_CLASS 32
         #DEFINE IDLE_PRIORITY_CLASS 64
         #DEFINE HIGH_PRIORITY_CLASS 128
         #DEFINE REALTIME_PRIORITY_CLASS 1600
   
         * Return code from WaitForSingleObject() if
         * it timed out.
         #DEFINE WAIT_TIMEOUT 0x00000102
   
         * This controls how long, in milli secconds, WaitForSingleObject()
         * waits before it times out. Change this to suit your preferences.
         #DEFINE WAIT_INTERVAL 200
   
         DECLARE INTEGER CreateProcess IN kernel32.DLL ;
            INTEGER lpApplicationName, ;
            STRING lpCommandLine, ;
            INTEGER lpProcessAttributes, ;
            INTEGER lpThreadAttributes, ;
            INTEGER bInheritHandles, ;
            INTEGER dwCreationFlags, ;
            INTEGER lpEnvironment, ;
            INTEGER lpCurrentDirectory, ;
            STRING @lpStartupInfo, ;
            STRING @lpProcessInformation
   
         DECLARE INTEGER WaitForSingleObject IN kernel32.DLL ;
            INTEGER hHandle, INTEGER dwMilliseconds
   
         DECLARE INTEGER CloseHandle IN kernel32.DLL ;
            INTEGER hObject
   
         DECLARE INTEGER GetLastError IN kernel32.DLL
   
         * STARTUPINFO is 68 bytes, of which we need to
         * initially populate the 'cb' or Count of Bytes member
         * with the overall length of the structure.
         * The remainder should be 0-filled
         start = long2str(68) + REPLICATE(CHR(0), 64)
   
         * PROCESS_INFORMATION structure is 4 longs,
         * or 4*4 bytes = 16 bytes, which we'll fill with nulls.
         process_info = REPLICATE(CHR(0), 16)
   
         * Start a copy of NOTEPAD (EXE name must be null-terminated)
         File2Run = "C:\WINNT\NOTEPAD.EXE" + CHR(0)
   
         * Call CreateProcess, obtain a process handle. Treat the
         * application to run as the 'command line' argument, accept
         * all other defaults. Important to pass the start and
         * process_info by reference.
         RetCode = CreateProcess(0, File2Run, 0, 0, 1, ;
            NORMAL_PRIORITY_CLASS, 0, 0, @start, @process_info)
   
         * Unable to run, exit now.
         IF RetCode = 0
            =MESSAGEBOX("Error occurred. Error code: ", GetLastError())
            RETURN
         ENDIF
   
         * Extract the process handle from the
         * PROCESS_INFORMATION structure.
         hProcess = str2long(SUBSTR(process_info, 1, 4))
   
         DO WHILE .T.
         * Use timeout of TIMEOUT_INTERVAL msec so the display
         * will be updated. Otherwise, the VFP window never repaints until
         * the loop is exited.
         IF WaitForSingleObject(hProcess, WAIT_INTERVAL) != WAIT_TIMEOUT
              EXIT
            ELSE
               DOEVENTS
            ENDIF
         ENDDO
   
         * Show a message box when we're done.
         =MESSAGEBOX ("Process completed")
   
         * Close the process handle afterwards.
         RetCode = CloseHandle(hProcess)
         RETURN
   
   
         ********************
         FUNCTION long2str
         ********************
         * Passed : 32-bit non-negative numeric value (m.longval)
         * Returns : ASCII character representation of passed
         *           value in low-high format (m.retstr)
         * Example :
         *    m.long = 999999
         *    m.longstr = long2str(m.long)
   
         PARAMETERS m.longval
   
         PRIVATE i, m.retstr
   
         m.retstr = ""
         FOR i = 24 TO 0 STEP -8
            m.retstr = CHR(INT(m.longval/(2^i))) + m.retstr
            m.longval = MOD(m.longval, (2^i))
         NEXT
         RETURN m.retstr
   
   
         *******************
         FUNCTION str2long
         *******************
         * Passed:  4-byte character string (m.longstr)
         *   in low-high ASCII format
         * returns:  long integer value
         * example:
         *   m.longstr = "1111"
         *   m.longval = str2long(m.longstr)
   
         PARAMETERS m.longstr
   
         PRIVATE i, m.retval
   
         m.retval = 0
         FOR i = 0 TO 24 STEP 8
            m.retval = m.retval + (ASC(m.longstr) * (2^i))
            m.longstr = RIGHT(m.longstr, LEN(m.longstr) - 1)
         NEXT
         RETURN m.retval
   						

2. Run the program by pressing CTRL+E, or clicking the Run control on the toolbar.
3. A copy of Notepad should be started.
4. Close the copy of Notepad. In the Visual FoxPro application, a message box containing the text "Processing completed" appears.