HWND hWnd = ::FindWindow(NULL, L"XXXXXXX");
	if (hWnd != NULL)
	{
		DWORD dwReadBytes;
		unsigned char *lpbuffer = (unsigned char *)malloc(10 * 1024 * 1024);;
		
		USES_CONVERSION;
		LPCSTR path = (LPCSTR)T2A(m_strDescPath); //m_strDescPath為一edit組件的成員變量

		HFILE splhandle = _lopen(path, 0);
		dwReadBytes = _lread(splhandle, lpbuffer, 10 * 1024 * 1024);

		COPYDATASTRUCT cpd; /*給COPYDATASTRUCT結構賦值*/
							//cpd.dwData = 1;                                                                                                         //標誌發送字符串
							//cpd.cbData = strlen("字符串")+1;
							//cpd.lpData = "字符串";
							//::SendMessage(hWnd,WM_COPYDATA,NULL,(LPARAM)&cpd);//發送！

		cpd.dwData = 1; //標誌發送CString類型
		cpd.cbData = dwReadBytes;
		cpd.lpData = lpbuffer;
		::SendMessage(hWnd, WM_COPYDATA, NULL, (LPARAM)&cpd); //發送！
	}

VS2013 中 CString類型轉換為LPCSTR類型