[Mono-list] Marshaling string on Windows returns Garbage??

[Jonathan Chambers]

You could try making the argument an out parameter and seeing if that
works. If so, there must be a bug in marshaling strings as return values.
Please file a bug in that case.

//C#
void CSharp_Out_String(out string str);

and
//C++
void CSharp_Out_String(char** str)
{
     const char* testValue = "test"
     *str = CoTaskMemAlloc(strlen(testValue)+1);
     strcpy(*str, testValue);
}

Thanks,
Jonathan

On Tue, Mar 13, 2012 at 8:21 AM, efontana <eric at fontanas.net> wrote:

> No, it's a std::string (there an above using namespace std)
>
> FWIW: I tried even doing this:
>
> const char* testValue = "test"
> char* s = CoTaskMemAlloc(strlen(testValue)+1);
> strcpy(s, testValue);
> return s;
>
> That also returns the 8 Question Marks.
>
> Even more interesting, if I change the signature to
> IntPtr CSharp_Return_String and use Marshal.PtrToStringAnsi, the string is
> correct!!
>
> If I use the IntPtr method, the C# wrapper will have to call
> Mashal.FreeCoTaskMem to avoid
> the leak, because I'm forced to allocate the string on the C++ side since
> the string is really
> embedded in either a std::string or a Qt QString.
>
>
>
> --
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