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Redirect

Franky Braem

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7 Jun 2000

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.

Example

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\command.com"
  
  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

Remarks

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

Resources

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

Check my website for updates.

License

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