Emptying CString

[mesajflaviu]

Where is m_sError declared?

In the header of CMyObject (derived from CObject).

[mesajflaviu]

Set a break point at the line

m_sError.Empty();

, start debugger, and when it breaks it this line press F11 to step into MS CString::Empty code to see whet happens and why.

After I used excel wrapper, I have in CString::m_pchData the buggy string: "Excel.Application.12" ... no matter what ... The workaround was to format

m_sError.Format(_T(""));

[VictorN]

After I used excel wrapper, I have in CString::m_pchData the buggy string: "Excel.Application.12" ... no matter what ... The workaround was to format

m_sError.Format(_T(""));

It is not a workaround.
Did you try to debug the CString::Empty code?

[mesajflaviu]

I will return in this afternoon with debugging results ... my app is not on my office ... See you soon.

[mesajflaviu]

Here is the debugging result:

void CString::Empty()
{
	if (GetData()->nDataLength == 0)       // m_pchData => "Some random error"
		return;
	if (GetData()->nRefs >= 0)             // m_pchData => "The same random error"
		Release();                         //  m_pchData => "Excel.Application.12"
	else
		*this = &afxChNil;
	ASSERT(GetData()->nDataLength == 0);   //  m_pchData => "Excel.Application.12"
	ASSERT(GetData()->nRefs < 0 || GetData()->nAllocLength == 0);  //  m_pchData => "Excel.Application.12"
}


void CString::Release()
{
	if (GetData() != _afxDataNil)      // m_pchData => "The same random error"
	{
		ASSERT(GetData()->nRefs != 0);
		if (InterlockedDecrement(&GetData()->nRefs) <= 0)     // m_pchData => "The same random error"
			FreeData(GetData());     //  m_pchData => "Excel.Application.12"
		Init();                      //  m_pchData => "Excel.Application.12"
	}
}

weird ... I have to dig in ...

[GCDEF]

At this point I'd be looking for memory corruption somewhere else in your program. CString::Empty works. You've probably stepped on something that's making your program act strangely but without causing a crash. Look for array overruns, etc.

[mesajflaviu]

Thank you ... I will looking for what you said.

[mesajflaviu]

I am thinking that the problem is inside of excel wrapper, that's why I get these garbage's in m_sError ... I am right ?

[VictorN]

Try to use the debugger to see how this CString instance was initialized.

[Arjay]

I am thinking that the problem is inside of excel wrapper, that's why I get these garbage's in m_sError ... I am right ?

I think the problem is you need to capture the error conditions (catch exceptions, check HRESULTS, etc) that cause the string to get populated, not check the string at some point later and wonder why it has something in it.

[mesajflaviu]

I think the problem is you need to capture the error conditions (catch exceptions, check HRESULTS, etc) that cause the string to get populated, not check the string at some point later and wonder why it has something in it.

I think you are perfectly right ... the problem is in somewhere else ...

[mesajflaviu]

I found the origin of the problem: before I work to excel wrapper, I opened registry and I didn't close them ... in case that everyone will face with the same problem ... thank you all !

[VictorN]

I found the origin of the problem: before I work to excel wrapper, I opened registry and I didn't close them ... in case that everyone will face with the same problem ... thank you all !

What does the "opening" registry have to do with the CString behaviour?

[2kaud]

If the underlying problem is memory corruption, then adding/changing some lines of code that doesn't directly address the problem (and which can be justified to have fixed the problem) is unlikely to fix the problem. The underlying problem could still be present but affecting some other part of the program in which it isn't so obvious - so the original symptoms 'disappear' so it looks like the problem has been fixed when it hasn't.

[mesajflaviu]

After all, I really found the problem: instead of

	// Get the Version information
	lRet = RegQueryValueEx(hKeyC, NULL, NULL, NULL, (BYTE*)(LPCTSTR)sVersion, &cSize);

I wrote:

	// Get the Version information
	lRet = RegQueryValueEx(hKeyC, NULL, NULL, NULL, (BYTE*)sVersion.GetBuffer(_MAX_PATH), &cSize);
	sVersion.ReleaseBuffer();

Thank you all for your attention.