Determining row indices in Sorting Comparison function

/////////////////////////////////////////////////////////////////////////////
// SortInfo structure definition
typedef struct tagSortInfo
{
	CListCtrl * pListControl;
	int	nColumnNo;
	bool nAscendingSortOrder;
}SortInfo;

/////////////////////////////////////////////////////////////////////////////
// CTestDialog dialog

class CTestDialog : public CDialog
{
public:
	CTestDialog(CWnd* pParent = NULL);   // standard constructor
//Dialog Data
	//{{AFX_DATA(CTestDialog)
	enum { IDD = IDD_DIALOG1 };
	CListCtrl	m_ListControl;
	//}}AFX_DATA
// Overrides
	// ClassWizard generated virtual function overrides
	//{{AFX_VIRTUAL(CTestDialog)
	protected:
	virtual void DoDataExchange(CDataExchange* pDX);    // DDX/DDV support
	//}}AFX_VIRTUAL

	static int CALLBACK SortList(LPARAM lpOne, LPARAM lpTwo, LPARAM lpArg);
// Implementation
	SortInfo m_SortInfo;
protected:
	// Generated message map functions
	//{{AFX_MSG(CTestDialog)
	//}}AFX_MSG
	afx_msg void OnHeaderClicked(NMHDR* pNMHDR, LRESULT* pResult);
	
	DECLARE_MESSAGE_MAP()
};

/////////////////////////////////////////////////////////////////////////////
//
void CTestDialog::OnHeaderClicked(NMHDR* pNMHDR, LRESULT* pResult)
{
	HD_NOTIFY *phdn = (HD_NOTIFY *) pNMHDR;
	if(phdn->iButton == 0)
	{
		if (phdn->iItem == m_SortInfo.nColumnNo)
			m_SortInfo.nAscendingSortOrder = !m_SortInfo.nAscendingSortOrder;
		else
			m_SortInfo.nAscendingSortOrder = TRUE;

		m_SortInfo.nColumnNo = phdn->iItem;
		m_SortInfo.pListControl = &m_ListControl;

		m_ListControl.SortItems( SortList,(DWORD)&m_SortInfo );
	}
	*pResult = 0;
}

int CALLBACK CTestDialog::SortList(LPARAM lpOne, LPARAM lpTwo, LPARAM lpArg)
{
	int nResult 			= 0;
	SortInfo * pSortInfo 		= (SortInfo *) lpArg;

	int nColumnNo 			= pSortInfo->nColumnNo;
	CListCtrl * pListControl 	= pSortInfo->pListControl;
	bool nAscendingSortOrder 	= pSortInfo->nAscendingSortOrder;

	int lFirstData = -1, lSecondData = -1;

	LV_FINDINFO FindInfo;
	// use LVFI_WRAP for cases where lpTwo represents a row before lpOne
	FindInfo.flags = LVFI_PARAM | LVFI_WRAP;
	FindInfo.lParam = lpOne;
	lFirstData = pListControl->FindItem(&FindInfo);

	FindInfo.lParam = lpTwo;
	// reduce searching time by setting the start row as lFirstData
	lSecondData = pListControl->FindItem(&FindInfo,lFirstData);
	// because we are searching for LPARAM sent to us, FindItem() on 
	// these values should always be successful
	ASSERT(lFirstData != -1); ASSERT(lSecondData != -1);

	CString FirstText = pListControl->GetItemText(lFirstData,nColumnNo);
	CString SecondText = pListControl->GetItemText(lSecondData,nColumnNo);
	
	int nCompareValue = FirstText.Compare(SecondText);
	nResult = nCompareValue * ((nAscendingSortOrder)?1:-1);
	// or
	// your own comparison code

	return nResult;
}