2015-03-02 16:17 GMT+08:00 Nikolay Sivov <bunglehead@gmail.com>:

On 02.03.2015 11:12, Shuai Meng wrote:

+�� �� HRESULT hres;
+�� �� BSTR bstr;
+�� �� WCHAR ret;
+
+�� �� TRACE("(%s)\n", debugstr_variant(arg));
+
+�� �� switch(V_VT(arg)) {
+�� �� case VT_NULL:
+�� �� �� �� return MAKE_VBSERROR(VBSE_ILLEGAL_NULL_USE);
+�� �� case VT_EMPTY:
+�� �� �� �� return MAKE_VBSERROR(VBSE_ILLEGAL_FUNC_CALL);
+�� �� case VT_BSTR:
+�� �� �� �� bstr = V_BSTR(arg);
+�� �� default:
+�� �� �� �� hres = to_string(arg, &bstr);
+�� �� �� �� if(FAILED(hres))
+�� �� �� �� �� �� return hres;
+�� �� }
+
+�� �� ret = bstr[0];
+�� �� if(ret == 0)
+�� �� �� �� return MAKE_VBSERROR(VBSE_ILLEGAL_FUNC_CALL);
+�� �� return return_short(res, ret);

Looks like you need to handle VT_NULL explicitly and after that only distinguish between VT_BSTR or the rest.

Also you're leaking memory and missing a 'break'.