Problem with carchive::

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VS2019

I am tying to save the contents of a CListBox into an archive file: Part of my store code:

C++

CFile xycFile(szFilePath, CFile::modeCreate | CFile::modeWrite);
		CArchive ar(&xycFile, CArchive::store);
		// Save the contents of the all channels box
		int Count = m_AllChannels.GetCount();
		ar << Count;
		int n = 0;

		for (int j = 0; j < Count; j++) {
			CString szTemp;
			n = m_AllChannels.GetTextLen(j);
			m_AllChannels.GetText(j, szTemp.GetBuffer(n));
			ar << m_AllChannels.GetItemData(j) << szTemp;
		}

For loading:

C++

CFile xycFile(szFilePath, CFile::modeRead);
CArchive ar(&xycFile, CArchive::load);
int Count;
ar >> Count;
for (int j = 0; j < Count; j++) {
    CString szTemp;
    int iPosn;
    ar >> iPosn >> szTemp;
    m_AllChannels.AddString(szTemp);
    m_AllChannels.SetItemData(iPosn, j);
}

I have debugged the Store section and checked that the values are correct for the ItemData and szTemp but when I load the data, I find that the integer values are correct but the CString szTemp is empty.

What I have tried:

Debugging and checking documentation.

Can anyone advise, many thanks.

Posted 23-Sep-24 22:49pm

Member 12724781

Updated 24-Sep-24 12:01pm

merano99

v2

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Comments

Rick York 24-Sep-24 22:02pm

I think I would write each channel's data separately, as independent operations that is. Correspondingly, I would read them independently. I would also adjust your GetText method to handle CStrings correctly, if you are going to use them. I try to avoid them as much as possible. I should also state that I detest CArchive and never use it.

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CPallini · Answer 1 · 2024-09-24T03:10:00

Solution 1

Quote:
m_AllChannels.GetText(j, szTemp.GetBuffer(n));

I would call

C++

szTemp.ReleaseBuffer();

before going on.

Posted 24-Sep-24 3:10am

CPallini

merano99 · Answer 2 · 2024-09-24T12:15:00

CPallini has already described the main error.
It is also clearly stated in the documentation.
If you use the pointer returned by GetBuffer to change the string contents, you must call ReleaseBuffer to update the internal state of CSimpleStringT before you use any other CSimpleStringT methods.
I also miss the closing of the archive and the file

xycFile.Close();
ar.Close();

This is all the more important if you want to use the file and the archive with the same name each time.
However, I would also recommend separate names for both access directions.