How to know when an external program ended?

[Starseeker]

Hello to all, this is my first post in this forum. Ok here we go....I need a little help with this problem

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Dim Value
Value = Shell("xxxxxx.exe", vbNormalFocus)
'***********************************
The above line is used by me to call up an external program call "xxxxxx.exe". What this program does is process some results, and output the result to a data file, and closed itself.

The content of the file will be read in the subsequent lines.

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Note: By default, the Shell function runs other programs asynchronously. This means that a program started with Shell might not finish executing before the statements following the Shell function are executed. ~taken from MSDN
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Now my question to fellow VB experts are, how in VB codes can I know when the program closes. I need to run the next line only after the program closed. It is important cuz the next line has a high chance of running even before the data file is generated. The data file must be generated before the next line can be run. Hope u guys can help. Thanks.

[JordanChris]

Look up the WaitForSingleObject API:


The recommended way is to use CreateProcess & WaitForSingleObject.

'This program needs a common dialog box, named CDBox
'  (To add the Common Dialog Box to your tools menu, go to Project->Components (or press CTRL-T)
'   and select Microsoft Common Dialog control)
Const INFINITE = &HFFFF
Const STARTF_USESHOWWINDOW = &H1
Private Enum enSW
    SW_HIDE = 0
    SW_NORMAL = 1
    SW_MAXIMIZE = 3
    SW_MINIMIZE = 6
End Enum
Private Type PROCESS_INFORMATION
    hProcess As Long
    hThread As Long
    dwProcessId As Long
    dwThreadId As Long
End Type
Private Type STARTUPINFO
    cb As Long
    lpReserved As String
    lpDesktop As String
    lpTitle As String
    dwX As Long
    dwY As Long
    dwXSize As Long
    dwYSize As Long
    dwXCountChars As Long
    dwYCountChars As Long
    dwFillAttribute As Long
    dwFlags As Long
    wShowWindow As Integer
    cbReserved2 As Integer
    lpReserved2 As Byte
    hStdInput As Long
    hStdOutput As Long
    hStdError As Long
End Type
Private Type SECURITY_ATTRIBUTES
    nLength As Long
    lpSecurityDescriptor As Long
    bInheritHandle As Long
End Type
Private Enum enPriority_Class
    NORMAL_PRIORITY_CLASS = &H20
    IDLE_PRIORITY_CLASS = &H40
    HIGH_PRIORITY_CLASS = &H80
End Enum
Private Declare Function CreateProcess Lib "kernel32" Alias "CreateProcessA" (ByVal lpApplicationName As String, ByVal lpCommandLine As String, lpProcessAttributes As SECURITY_ATTRIBUTES, lpThreadAttributes As SECURITY_ATTRIBUTES, ByVal bInheritHandles As Long, ByVal dwCreationFlags As Long, lpEnvironment As Any, ByVal lpCurrentDriectory As String, lpStartupInfo As STARTUPINFO, lpProcessInformation As PROCESS_INFORMATION) As Long
Private Declare Function WaitForSingleObject Lib "kernel32" (ByVal hHandle As Long, ByVal dwMilliseconds As Long) As Long
Private Function SuperShell(ByVal App As String, ByVal WorkDir As String, dwMilliseconds As Long, ByVal start_size As enSW, ByVal Priority_Class As enPriority_Class) As Boolean
    Dim pclass As Long
    Dim sinfo As STARTUPINFO
    Dim pinfo As PROCESS_INFORMATION
    'Not used, but needed
    Dim sec1 As SECURITY_ATTRIBUTES
    Dim sec2 As SECURITY_ATTRIBUTES
    'Set the structure size
    sec1.nLength = Len(sec1)
    sec2.nLength = Len(sec2)
    sinfo.cb = Len(sinfo)
    'Set the flags
    sinfo.dwFlags = STARTF_USESHOWWINDOW
    'Set the window's startup position
    sinfo.wShowWindow = start_size
    'Set the priority class
    pclass = Priority_Class
    'Start the program
    If CreateProcess(vbNullString, App, sec1, sec2, False, pclass, _
    0&, WorkDir, sinfo, pinfo) Then
        'Wait
        WaitForSingleObject pinfo.hProcess, dwMilliseconds
        SuperShell = True
    Else
        SuperShell = False
    End If
End Function
Private Sub Form_Load()
    'KPD-Team 1998
    'URL: [url]http://www.allapi.net/[/url]
    'E-Mail: [email][email protected][/email]
    'Set the dialog's title
    CDBox.DialogTitle = "Choose an EXEC-File ..."
    'Error when canceled
    CDBox.CancelError = True
    'Set the dialog's filter
    CDBox.Filter = "EXEC-Files (*.exe)|*.exe|All files (*.*)|*.*"
    'Show the 'Open File'-dialog
    CDBox.ShowOpen
    'Execute the program
    SuperShell CDBox.filename, Left$(CDBox.filename, Len(CDBox.filename) - Len(CDBox.FileTitle)), 0, SW_NORMAL, HIGH_PRIORITY_CLASS
    End
End Sub

[Starseeker]

Thanks Jordan.

I don't need a dialog box to open exexcutable files though. "xxxxx.exe" is all I need to run. I will try it out later in the day to see if there is any problem.

[dsheller]

Just an idea, but declare value as long, shell only returns the process id of an executeable being ran so a variant really isnt needed, which is what you do when you leave a variable undeclared.

[Starseeker]

Thanks, the below are the codes I used eventually, and ya, it works.

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Public Function SyncShellCmd(CmdStr As String, ApplicationFocus As Long) As Boolean
'Run the application by the CmdStr, and exit when the program terminated, Application focus specific
'the focus of the application. e.g vbNormalFocus
Dim lPid As Long 'The task ID of the started program
Dim lHnd As Long ' handle to object to wait for
Dim lRet As Long 'Return value of WaitForSingleObject()

SyncShellCmd = False
If CmdStr = "" Then Exit Function
lPid = Shell(CmdStr, ApplicationFocus)
If lPid <> 0 Then
'Get a handle to the shelled process.
lHnd = OpenProcess(SYNCHRONIZE, 0, lPid)
'If successful, wait for the application to end and close the handle.
If lHnd <> 0 Then
lRet = WaitForSingleObject(lHnd, INFINITE) 'no time out
CloseHandle (lHnd)
SyncShellCmd = True
End If
'MsgBox "Just terminated.", vbInformation, "Shelled Application"
End If

End Function
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