Re: Convert CString to LONG.

From:
"Doug Harrison [MVP]" <dsh@mvps.org>
Newsgroups:
microsoft.public.vc.mfc
Date:
Thu, 26 Jun 2008 11:05:14 -0500
Message-ID:
<m2f764h2m8rfff5udsuo2gql9hvafl1mc1@4ax.com>
On Thu, 26 Jun 2008 08:49:48 -0700 (PDT), Control Freq
<nick@nhthomas.freeserve.co.uk> wrote:

OK,
One more question, for now:

In a class I have a CString called ErrorString.
I also have a public method which is used to get the ErrorMessage.

LPCSTR doesn't work when _UNICODE is defined, so I now have:

#ifdef _UNICODE
 LPCTSTR GetLastError(void) { return ErrorMessage; }
#else
 LPCSTR GetLastError(void) { return ErrorMessage; }
#endif

Is there a better way?


That's kinda missing the point of "T". Just use:

  LPCTSTR GetLastError(void) { return ErrorMessage; }

That said, given that ErrorMessage is a CString, you had better make sure
that its lifetime exceeds the lifetime of the LPCTSTR returned by
GetLastError, because the latter is a pointer to the CString's internal
data. While this doesn't address that issue, I would tend to return the
CString by const reference instead:

  const CString& GetLastError(void) { return ErrorMessage; }

This way, users can use the result of GetLastError as a CString, and if you
pass it to a function expecting a CString, reference-counting will avoid
making a new CString, which is necessary if you return LPCTSTR.

--
Doug Harrison
Visual C++ MVP

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