Re: Bad pointer on CString

Scot T Brennecke <>
Tue, 22 Sep 2009 02:29:59 -0500
David Webber wrote:

"Alexh" <> wrote in message

class Myclass : public CObject

CString MyCstring;


The debugger reports that the CString has a bad pointer (all 0's).

*When* is it reporting it?

It isn't at all clear to me that the internal pointer of a CString
cannot legally be NULL. I've always thought it could be, and that the
CString methods allowed for it.

I can't remember if I ever checked, but even if I did, it may be
different in different implementations. But I have always allowed for
the possibility that the standard cast


might return NULL. If it can, and you assume it doesn't, then you
might run into trouble. But (if I'm right) I can't think where else
the debugger might report a problem?


Nope. Check out the code for the ATL::CStringT (really the ATL::CSimpleStringT) class templates. You'll see that the m_pszData
member should never be NULL. The (LPCTSTR) cast returns the m_pszData as a string pointer, but it's also expected to be a valid
address that can be manipulated to get to the CStringData object for that string.

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