I've looked through this thread and still have quetions.
Suppose In visual studio 2005, I write the following

#pragam managed
class ManagedWrapper
{
    void CallUnmanagedMethod() // The unmanaged class /method is
imported from a C++ DLL generated by vc 6.0
    {
         std::string* inputString = new string();
         inputString = "Text";
         UnmanagedClass uc;
        uc.Run(inputString); // signature uc.Run(string* input)
    }
}

since std::string* is unmanaged. So it's a mix mode code. So
inputString unmanaged. Why can't I do something like that?
So in this case I can work without Marshal.StringToHGlobalAnsi if I
don't have to copy content from managed String, right?

Second question is,
I also tried this,
String^ text = "AAA";
char* buffer = (char*)Marshal.StringToHGlobalAnsi(text).ToPtr();
std::string input;
input = buffer;
UnmanagedClass uc; // imported from a C++ DLL generated by VC 6.0
uc.Run(input);

Now the questions is,
This piece of code compile and link perfectly. But when Í run it, my
unmanaged class just got some garbage string. If there are other
parameter after string,
those parameter will be filled with garbage data. But unmanaged DLL
doesn't complain. It just cast the input into the right type.
Why is it?

Thanks a lot if anyone can help me.