Send WM_COPYDATA from Python - Partial Solution

I wanted to send a WM_COPYDATA message from a Python application to a Windows application.

Here is the code both Python and C++ which I got work with the only caveat that the string in szData is not received correctly. This example is a very tiny modification of the code posted here: https://groups.google.com/forum/#!topic/comp.lang.python/z3QS7Ic80mU


Python code:

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import struct import win32con import win32gui import array class COPYDATATYPE(Structure): _fields_ = [("nNum", c_ulong), ("szData", c_char_p)] class COPYDATASTRUCT(Structure): _fields_ = [("dwData", c_ulong), ("cbData", c_ulong), ("lpData", POINTER(COPYDATATYPE))] cpyData = COPYDATATYPE(17, '123456789') cds = COPYDATASTRUCT(c_ulong(1), c_ulong(sizeof(cpyData)), pointer(cpyData)) # try to send a message win32api.SendMessage(hwnd, win32con.WM_COPYDATA, 0, addressof(cds))

C++ code:

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case WM_COPYDATA: pCDS = (COPYDATASTRUCT*)lParam; if (pCDS->dwData == 1) { struct COPYDATATYPE { long nNum; char * szData; }; int count = pCDS->cbData; PVOID data = pCDS->lpData; if (data != NULL) { COPYDATATYPE *cp = (COPYDATATYPE *)data; int i = cp->nNum; // The following line does not work. const char* message = cp->szData; } } break;

I also found use in reading this: http://www.qsl.net/dl4yhf/yhf_comm/yhf_comm_info.htm#find_window_handle