Question

Ok, so this piece of code works fine in the Debug but not in Release build.

int AddString(LPCTSTR lpszString, ...)
{
    RArray<LPCTSTR> strings;
    va_list args;
    va_start(args, lpszString);
    do
    {
        strings.Add(lpszString); 
    } while (lpszString = va_arg(args, LPCTSTR));
    va_end(args);

    // ... rest of code ...
}

It seems in Release, va_arg just returns an extra value containing rubbish. So if I pass on 3 parameters: I fetch 3 in Debug and miraculously 4 in Release… How is this possible? Using VS2010 btw.

(RArray is just a simple template class comparable to MFC’s CArray, does not influence results)

Thanks!

Edit: I call it like this

AddString(_T("Hello, world!"), _T("Hallo, wereld!"), _T("Hallo, Welt!"));

Answer 1

You’re doing it the wrong way and you’re just lucky with the debug build.

Notice that va_arg does not determine either whether the retrieved argument
is the last argument passed to the function (or even if it is an element
past the end of that list). The function should be designed in such a way
that the amount of parameters can be inferred in some way by the values of
either the named parameters or the additional arguments already read.

Supply either the length of the list in an integer or pass a NULL at the end of the list.