Changing an unmanaged string from managed code

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Roy Chastain - 25 Oct 2004 19:47 GMT

I have successfully loaded a MANAGED C++ dll from an UNmanaged C++ program. I can even manage to call methods in classes in that
DLL. What I need to know is how to pass a string back to the UNmanaged code from the managed code.

public __gc __interface KMS::Transport::Managed::IManager
{
    public:
        virtual int Initialize (HRESULT *result, [System::Runtime::InteropServices::Out] String *error_text) = 0;
};

public __gc class KMS::Transport::Managed::Manager: public IManager
{

    public:
    Manager (void)
    {
    }

    int Initialize (HRESULT *result, [System::Runtime::InteropServices::Out] String *error_text)
    {
        *result = S_OK;
        // how do I set the value of error_text here
    }
}
-------------------------------------------
Roy Chastain
KMSystems, Inc.

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Roy Chastain - 26 Oct 2004 17:28 GMT

Well, I found something that appears to work.
Change the signature of the Initialize method to use .... String **error_text instead of String *error_text
Then *error_text = new String("Hello");

The unmanaged code looks like
        int                        ret_val
        BSTR                    msg = _bstr_t(LPVOID(NULL));
        HRESULT            result1;
        result = manager->Initialize(&result1,&msg,&ret_val);
        wprintf(LPWSTR(msg));
        SysFreeString(msg);

>I have successfully loaded a MANAGED C++ dll from an UNmanaged C++ program. I can even manage to call methods in classes in that
>DLL. What I need to know is how to pass a string back to the UNmanaged code from the managed code.
[quoted text clipped - 22 lines]
>Roy Chastain
>KMSystems, Inc.

-------------------------------------------
Roy Chastain
KMSystems, Inc.

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Changing an unmanaged string from managed code

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