How can I call a dll from VB.NET for a particle simulation?

  • Thread starter Pauly Man
  • Start date
In summary, the dll must be in the same folder as the lib file and the function for export must be called "RungeKutta".
  • #1
Pauly Man
129
0
I've created a dll in c++ that runs a 4th order Runge-Kutta on user supplied data. I want to use it in a particle simulation, which I already have in vb.net. The trouble is I have no idea how to call the dll from within vb, any ideas?

ps- I've tried using the info provided on msdn, but I'm not sure if I'm doing it right. Basically the dll file is called "RungeKuttaDLL.dll", the lib file is called "RungeKuttaDLL.lib" and the function for export within the dll is called "RungeKutta". msdn gave me this info:

Private Declare Function RungeKutta Lib "c:\Documents and Settings\PB Customer\My Documents\Visual Studio Projects\VB\NumericalMethods\RungeDLL\RungeKuttaDLL.dll"(ByVal X0 As Double, ByVal Y0 As Double, ByVal H As Double, ByVal N As Integer) As Double

It doesn't work though.
 
Last edited:
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  • #2
Put your DLL in your bin folder. Then in your code at the top type "Imports ..." (... = whatever namespace is in your dll). Now you have access to your classes in the dll.
 
  • #3
I still can't get it to work. I looked at some examples on the net, and they all seem to work, but only have one function in the dll, or are API calls. I get an error message when I try and compile, and it tells me it can't find an entry point called RungeKutta. I've looked all over the ent, and there is nothing of use that I can find. I may just give up and work out how to program it all in c++, vb seems way too complicated and too much trouble, which is an oxymoron when you think about it.
 
  • #4
Your namespace and or classes must not be setup right then. Copy your code in here.

btw, why are you using VB and not C#? C# is a lot closer to C++ and Java.
 
  • #5
Module RungeDLL

Declare Function RungeKutta Lib "c:\Documents and Settings\PB Customer\My Documents\Visual Studio Projects\VB\NumericalMethods\RungeDLL\bin\RungeKuttaDLL.dll" Alias "RungeKutta" (ByVal X0 As Double, ByVal Y0 As Double, ByVal H As Double, ByVal N As Integer) As Double

End Module




Imports RungeDLL

Public Class Form1
Inherits System.Windows.Forms.Form

#Region " Windows Form Designer generated code "

Public Sub New()
MyBase.New()

'This call is required by the Windows Form Designer.
InitializeComponent()

'Add any initialization after the InitializeComponent() call

End Sub

'Form overrides dispose to clean up the component list.
Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
If disposing Then
If Not (components Is Nothing) Then
components.Dispose()
End If
End If
MyBase.Dispose(disposing)
End Sub

'Required by the Windows Form Designer
Private components As System.ComponentModel.IContainer

'NOTE: The following procedure is required by the Windows Form Designer
'It can be modified using the Windows Form Designer.
'Do not modify it using the code editor.
<System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
'
'Form1
'
Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
Me.ClientSize = New System.Drawing.Size(292, 266)
Me.Name = "Form1"
Me.Text = "Form1"

End Sub

#End Region

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
RungeKutta(0.0, 0.0, 0.2, 5)
End Sub
End Class



I have never really thought about using c# before, maybe I should.
 
  • #6
oh it's a regular C++ DLL, you know there is also a C++.net :smile:

anyway here you go
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfSystemRuntimeInteropServicesDllImportAttributeClassTopic.asp [Broken]
 
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  • #7
I'm using c++.net, well vs.net anyway.
 
  • #8
I've worked it out. I don't fully understand why it works now, but it does, so Hooray!
 

What is a DLL and how is it used in VB.NET?

A DLL (Dynamic Link Library) is a file that contains code and resources that can be used by multiple programs. In VB.NET, DLLs are often used to store common functions or features that can be shared across different applications.

How do I call a DLL from VB.NET?

To call a DLL from VB.NET, you first need to add a reference to the DLL in your project. Then, you can use the "Imports" statement to access the DLL's classes, methods, and properties in your code.

Can I pass parameters to a DLL in VB.NET?

Yes, you can pass parameters to a DLL in VB.NET. You can do this by using the "DllImport" attribute in your code to specify the DLL and its parameters. You can also use the "ByRef" keyword to pass parameters by reference instead of by value.

What are the benefits of using DLLs in VB.NET?

Using DLLs in VB.NET can provide several benefits, including code reusability, easier maintenance, and improved performance. By storing common functions in a DLL, you can save time and effort by not having to rewrite the same code in multiple applications. DLLs can also be easily updated or replaced without affecting the rest of the program, making maintenance easier. Additionally, using DLLs can improve performance by reducing memory usage and speeding up execution time.

Are there any potential drawbacks to using DLLs in VB.NET?

One potential drawback of using DLLs in VB.NET is that it can add complexity to your project. If multiple DLLs are used, it may be more difficult to keep track of dependencies and ensure that all required DLLs are included in the final application. Additionally, if a DLL is not properly coded or maintained, it could cause errors or crashes in your application. It is important to carefully manage and test DLLs to avoid potential issues.

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