Public Function TestMethod(ByVal p1 As String) As String
 TestMethod = p1 & "_test"
End Function

#include <iostream>
#include <conio.h>

using namespace std;

int main ()
{
    cout << "Hello world!!!\n";
    _getch();
    return 0;
}

#import "C:\MyProject\bin\Debug\TestMethodDll.tlb" raw_interfaces_only  

::CoInitialize(NULL);
ClassInterfacePtr pIClass(__uuidof(Class1));

char Buffer[]="hello";
 
USES_CONVERSION;
 BSTR bstr_put = A2BSTR( (LPCSTR)Buffer ); 

pIClass->TestMethod( &bstr_put);  

 CoUninitialize();