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Posted 3 May 2000


, 7 Jun 2000
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An ATL-control for redirecting stdout/stdin
  • Download demo project - 6 Kb
  • Download source - 21Kb
  • Download control (ver. Windows '98) - 26 Kb
  • Redirect

    This control makes it possible to redirect the stdin/stdout of a console-application to your program. It's even possible to redirect MS-DOS commands to your application. I've written this project in Visual C++ 6.0 with ATL 3.0, because you can't use multithreading in Visual Basic.

    Properties of the Application Object

    Name Type R/W Description
    BufferSize Integer Read/Write Returns or sets the buffersize that is used to read the stdout. Default is 8192.
    LastErrorNumber Long Read Returns the last windows errornumber.
    Name String Read/Write The name of the console-application.
    Running Boolean Read Returns true if the console-application is running.
    Wait Long Read/Write Sets the milliseconds to wait for checking the stdout. If the console-application runs a long time, make sure you set this property, because otherwise your program will not have enough time to process other tasks.

    Methods of the Application Object

    Name Returns Parameters Description
    Start eStartResult / Starts the console-application. Returns laAlreadyRunning when the console-application was already started. Retuns laWindowsError when an error occurred. Returns laOk when the console-application is started correctly.
    Stop / Stops the console-application.
    Write Boolean Byval sCommandString As String Writes sCommandString to the stdin of the console-application. Returns false when an error ocurred.

    Events of the Application Object

    Name Parameters Description
    DataReceived sData As String The data from the stdout of the console-application.
    ProcessEnded / The console-application ended.


    The following VB-Example starts the MS-DOS prompt in Windows'98 and executes the dir command. The received data is displayed in a TextBox.

    Dim WithEvents oLaunch As redirectlib.Application
      Set oLaunch = New redirectlib.Application
      oLaunch.BufferSize = 8192
      oLaunch.Wait = 1000
      oLaunch.Name = "c:\windows\"
      Select Case oLaunch.Start
          Case laAlreadyRunning
              MsgBox "Already running !"
          Case laWindowsError
              MsgBox "Windows error: " &
      CStr(oLaunch.LastErrorNumber) & "!"
          Case laOk
              oLaunch.Write "dir" + vbCrLf
              oLaunch.Write "exit" + vbCrLf
      End Select
      Private Sub oLaunch_DataReceived(ByVal sData As String)
          txtOutput.Text = txtOutput.Text + sData
          txtOutput.SelStart = Len(txtOutput.Text)
      End Sub
      Private Sub oLaunch_ProcessEnded()
          MsgBox "Program stopped"
      End Sub


    When you use the MS-prompt in Windows NT (cmd.exe) then you can stop the console-application with the Stop-method. However in Windows '98 this doesn't work. Why I don't know. You can solve this by writing the "exit"-command to stdin of the console-application. Other console-applications work fine with NT and '98.

    The control was tested on Windows NT and Windows '98.

    The control is written with Visual C++ 6.0 using ATL 3.0. The control was tested with Visual Basic 6.0


    These are resources I've used to create this project :

    1. HOWTO: Spawn Console Processes with Redirected Standard Handles
    2. Redirecting Standard Output to a CEdit Control
    3. Redirect Output of CMD.EXE to a Pipe

    Check my website for updates.


    This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

    A list of licenses authors might use can be found here


    About the Author

    Franky Braem
    Web Developer
    Belgium Belgium
    Programmer since 1991 using C/C++/Visual Basic and Java. Playing with wxWindows at home.

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    Comments and Discussions

    GeneralProject request Pin
    aryanabc29-Jun-09 21:02
    memberaryanabc29-Jun-09 21:02 

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