Question

I’m looking for a way to automatically deallocate an array of wchar_ts – kind of like an autopointer (I’m not really aquainted with std::auto_ptr, but I think it cannot be used for arrays).

The code I have right now is this:

/* volume is of type wstring,
 * hr is of type HRESULT, 
 * VSS_PWSZ equals wchar_t* 
 */

VSS_PWSZ pwszVolume = new wchar_t[volume.size() + 1];
std::copy(volume.begin(), volume.end(), &pwszVolume);
pwszVolume[volume.size()] = 0;

hr = pDiffMgmt->QueryDiffAreasOnVolume(pwszVolume, &pEnumMgmt);

delete[] pwszVolume;
pwszVolume = NULL;

I don’t really get why this stupid function cannot take a const wchar_t*, otherwise I could just pass volume.c_str().

So far so good, I think my code solves this problem, but now the memory management is getting more complicated: I would have to duplicate the delete[] code to account for exceptions which might be thrown (and which I do not want to catch at this point.)

Is there a way I can get pwszVolume to be deallocated automatically when the current scope is left?

Answer 1

Use std::vector<wchar_t> it is your basic C++ array (or std::wstring if you want to manipulate it like a string).

std::vector<wchar_t> pwszVolume(volume.begin(), volume.end());
pwszVolume.push_back(0);

hr = pDiffMgmt->QueryDiffAreasOnVolume(&pwszVolume[0], &pEnumMgmt);

The question may be. What does QueryDiffAreasOnVolume() do with the data?
Maybe you do not need to copy it out.