How to Send Keystrokes from VB App to MS-DOS App

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The information in this article applies to:

• Professional and Enterprise Editions of Microsoft Visual Basic, 16-bit only, for Windows, version 4.0

SUMMARY

This article demonstrates a technique you can use to to send keystrokes to a Microsoft MS-DOS-based application from a Microsoft Visual Basic application running on Microsoft Windows 3.x or Microsoft Windows 95. This method does not work with Microsoft Windows NT.

MORE INFORMATION

The Visual Basic for Windows SendKeys function can send keystrokes to the currently active window as if the keystrokes had been typed at the keyboard. Although it is not possible to send keystrokes to an application that is not based on Windows by using SendKeys directly, you can place text on the Clipboard and use the SendKeys function to paste that text into an MS-DOS-based application that is running in a window or minimized as an icon.

To run an MS-DOS-based application in a window, you must be running in Windows 386 enhanced mode. You must also make sure that the MS-DOS-based application's .PIF file has been set to display the application in a window rather than full screen. Use the Windows PIF Editor to make this modification, if necessary.

Step-by-Step Example

The following example demonstrates how to send keystrokes to an MS-DOS session running in a window:

1. Start an MS-DOS session running in a window.

2. Start Visual Basic for Windows and start a new project.

3. Enter the following into the general declarations section of the form:

         Dim progname As String
   

4. Put two labels on the form. Change the first label's caption to "MS-DOS App Title." Change the second label's caption to "Keys to send."

5. Put two text boxes on the form next to each of the labels. Delete the default contents of these text boxes. These controls are used to allow the user to enter the MS-DOS-based application's window title and the keystrokes to send to it. Change the Name property of these text boxes to "DosTitle" and "DosKeys" respectively.

6. Put a command button on the form, and change its caption to "Send keys."

7. Add the following code to the Command1 button click event procedure:

      Private Sub Command1_Click()
         'Ensure that progname is set to the titlebar of Visual Basic while
         ' running.
         progname = "Project1 - Microsoft Visual Basic [run]"
         clipboard.Clear
         clipboard.SetText DosKeys.Text + Chr$(13)  ' Append a <CR>.
         AppActivate DosTitle.Text
         SendKeys "% ep", 1
         AppActivate progname
      End Sub
   
      If the text that you send is the DIR command or another command that
      takes time, the AppActivate call immediately following the SendKeys
      call can interrupt the processing. The AppActivate call should be
      placed in a timer with the appropriate interval set, and the timer
      should be enabled in the command_click procedure. The timer should
      be disabled before exiting the timer.
   
   

8. Run the program.

9. Enter the window title of the MS-DOS-based application into the DosTitle text box. The default window title for an MS-DOS session is "MS-DOS Prompt".

10. Enter the keystrokes to send into the DosKeys text box (for

        example, DIR).
    

11. Click the Send Keys button. The keystrokes are sent to the

        Clipboard and then pasted into the MS-DOS window.