gcnew, interop, and OutOfMemoryException

[TFobear]

I think I am getting the hang of memory in c++/cli. So this native function:

int WriteToBuffer(HDIB hdib, int nFormat, BYTE* pBuffer, int nbMax);

can be wrapped like this:

int Toolkit::Dib::WriteToBuffer(System::IntPtr hdib, int nFormat, array<Byte>^&#37; pBuffer, int nbMax)
{
	pin_ptr<Byte> p = &pBuffer[0];
	return ::WriteToBuffer((HDIB)hdib.ToPointer(), nFormat, (BYTE*)p, nbMax);
}

and memcpy can be used to convert a String^ to a char* like this:

const char * SystemStringToCSTR(System::String^ sz)
{
	char ret [255];
	IntPtr hglobal;
	
	hglobal = Marshal::StringToHGlobalAnsi(sz);
	memcpy_s(ret, 255, (char*)hglobal.ToPointer(), strlen((char*)hglobal.ToPointer()));
	Marshal::FreeHGlobal(hglobal);

	return ret;
}

(*Note*)
the above function does not work, because ret is an adress of memory that does not last beyond this function. To surcumvent this for the time being I made "char ret" into "static char ret", however this has an issue. If you were to call this function twice in the same callee, it will overright itself:

char * one = SystemStringToCSTR(first);
char * two = SystemStringToCSTR(last);

one now is overwritten. For my case it (sort of) works because I am only calling it once per function so far. however, this is not very scalable.