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copied!<p>Because library_version requires a char**, they don't want you to allocate the characters (as you're doing with create_string_buffer. Instead, they just want you to pass in a reference to a pointer so they can return the address of where to find the version string.</p> <p>So all you need to do is allocate the pointer, and then pass in a reference to that pointer.</p> <p>The following code should work, although I don't have obo.dll (or know of a suitable replacement) to test it.</p> <pre><code>from ctypes import * _OBO_C_DLL = 'obo.dll' STRING = c_char_p _stdcall_libraries = dict() _stdcall_libraries[_OBO_C_DLL] = WinDLL(_OBO_C_DLL) OBO_VERSION = _stdcall_libraries[_OBO_C_DLL].OBO_VERSION OBO_VERSION.restype = c_int OBO_VERSION.argtypes = [POINTER(STRING)] def library_version(): s_res = c_char_p() res = OBO_VERSION(byref(s_res)) if res != 0: raise Error("OBO error %r" % res) return s_res.value library_version() </code></pre> <p>[Edit]</p> <p>I've gone a step further and written my own DLL that implements a possible implementation of OBO_VERSION that does not require an allocated character buffer, and is not subject to any memory leaks.</p> <pre><code>int OBO_VERSION(char **pp_version) { static char result[] = "Version 2.0"; *pp_version = result; return 0; // success } </code></pre> <p>As you can see, OBO_VERSION simply sets the value of *pp_version to a pointer to a null-terminated character array. This is likely how the real OBO_VERSION works. I've tested this against my originally suggested technique above, and it works as prescribed.</p>

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