Question : Unicode/STL/Varargs problem

Hi.  I am very stumped by this problem.
I have a small Unicode MFC project (_UNICODE is defined).
VC 6.0 / Win2K .  Also it uses STL strings.

Building the code below works ok.
But uncommenting the line in test_msgs() causes
incorrect strings to pop up in the dialog.
And if the function is called a 2nd time, the app crashes.

Any ideas?  Thank you very much.

#include
#include

typedef unsigned short unichar;

class ustring : public std::basic_string
{
public:
     ustring() {}
     ustring(const unichar *rhs) : std::basic_string(rhs) {}
     ustring(const ustring &rhs) : std::basic_string(rhs) {}
};

static void popup_msg(const ustring &msg, ...) {
     wchar_t buf[2048];

     va_list args;
     va_start(args, msg);
     vswprintf(buf, msg.c_str(), args);
     va_end(args);

     AfxMessageBox(CString(buf),MB_OK);
}

void test_msgs(void) {
     wchar_t wbuf[80];

     lstrcpy(wbuf,L"WChar test: %s");
     CString cstr="test 10";

     // When I uncomment the following line, it breaks
     //ustring ustr1=L"test 11";

     ustring ustr2(wbuf);
     popup_msg(ustr2,cstr);
}

Answer : Unicode/STL/Varargs problem

ahhh - sorry I should have looked more closely - this is a known problem with using references and the va_* macros see

http://support.microsoft.com/support/kb/articles/Q119/3/94.asp

you can use their fix or you could just change your code

static void popup_msg2(const unistr *msg, ...) {
   wchar_t buf[2048];

   va_list args;
   va_start(args,msg);
   // the following line crashes
   vswprintf(buf,msg->c_str(),args);
   va_end(args);

   DISPLAY_STR(buf);
}

...

popup_msg2(&ustr,wbuf2);