Hi sheng thanks for this link. I am now trying to import my unmanaged dll &
creating a managed wrapper on it as shown below:

[DllImport("C:\\New Folder\\unmanaged.dll", EntryPoint = "testfunction"
,CallingConvention= CallingConvention::Cdecl)]
String *  LonString( const teststructure& v, String * s, uint nb );

public:
String *    LonNeuronIdString( const TLonNeuronId& v, String * s, uint nb )
{
return ::NaCppLibLib::LonNeuronIdString( v, s, nb ); //passing to unmanaged
}
First of all can you please point out the mistake in it. I am no able to
access the structure in VB.Net application. I have included the structure in
namespace.

Thanks.