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Title | Use a .NET system DLL in a Visual Basic 6 program |
Description | This example shows how to use a .NET system DLL in a Visual Basic 6 program. |
Keywords | VB .NET, DLL, VB .NET, System DLL, WebClient, downloadFile |
Categories | Software Engineering, Windows, VB.NET, Miscellany |
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For more details, see the article Calling .Net Classes from Visual Basic 6 by Peter Aitken.
This example contains a VB 6 program that uses the .NET System namespace. The steps to prepare the example are:
- Register the system.dll assembly created by the .NET Framework as a COM object:
Open a DOS command window.
Type: CD C:\WINDOWS\Microsoft.NET\Framework\v1.1.4322
Type: regasm system.dll
- Add a reference to the DLL.
- Create a Visual Basic project.
- Select the Project menu's References command.
- In the References dialog, click Browse.
- Navigate to C:\WINDOWS\Microsoft.NET\Framework\v1.1.4322.
Select the system.tlb file and click Open.
*** Important *** Select the ".tlb" file not the ".dll" file.
The ".tlb" file contains extra information that Visual Basic
needs to use the DLL.
- Click OK to close the References dialog.
- Use the DLL in the VB project (see below).
When the program starts, the Form_Load event handler creates a new System.WebClient object from the .NET System DLL. It uses that object's downloadFile method to copy a file from the Internet to a local file. It then loads the picture and displays it.
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Private Sub Form_Load()
Dim wc As System.WebClient
' Create a WebClient.
Set wc = New System.WebClient
' Download a picture file.
wc.downloadFile _
"http://www.vb-helper.com/vb_prog_ref.jpg", _
App.Path & "\vb_prog_ref.jpg"
' Display the image.
Set Image1.Picture = LoadPicture(App.Path & _
"\vb_prog_ref.jpg")
' Size the form to fit.
Me.Width = 2 * Image1.Left + Image1.Width + Me.Width - _
Me.ScaleWidth
Me.Height = 2 * Image1.Top + Image1.Height + Me.Height _
- Me.ScaleHeight
End Sub
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