in VB.Net how to catch a buffer returned from a c function

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C

VB

i have DLL in C in which one of my function will return a char buffer.

How do i get the buffer in VB.Net

I am using following code in C and VB.NET

C Code

int my_buff(char * buff)
{
   memcpy(buffer,"testtest",8);

   return 1;

}

VB.Net Code

<dllimport("mydll.dll",charset:->_

Overloads Shared Function my_buff(ByRef s() As Char) As Integer
End Function


Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

Dim lo as String=""

Dim j as Integer=0

j=my_buff(lo)

End Sub

how can i get the buffer that is written in C?