Sort list (numeric/text/float/date) using callback

////////////////////////////////////////////////////////////////////////  
////////
// by Max Poliashenko - rewritten version of class proposed by Iuri Applonio
// This class will sort a List control by a column of text, integer, float or
// date/time type. It could be easily extended for other data types.
// February 11, 1998
//

class CSortClass
{
public:
	enum EDataType {dtNULL, dtINT, dtSTRING, dtDATETIME, dtDEC};
	
	CSortClass(CListCtrl * _pWnd, const int _iCol);
	virtual ~CSortClass();
	void Sort(bool bAsc, EDataType _dtype);
	
protected:
	CListCtrl * pWnd;
	
	static int CALLBACK Compare(LPARAM lParam1, LPARAM lParam2, LPARAM 
		lParamSort);
	
	struct CSortItem
	{
		CSortItem(const DWORD _dw, const CString &_txt);
		DWORD dw; 
		CString txt;
	};
};


////////////////////////////////////////////////////////////////////////  
/////
// CSortClass

CSortClass::CSortClass(CListCtrl * _pWnd, const int _iCol)
{
	pWnd = _pWnd;
	
	ASSERT(pWnd);
	int max = pWnd->GetItemCount();
	DWORD dw;
	CString txt;
	
	// replace Item data with pointer to CSortItem structure
	for (int t = 0; t < max; t++)
	{
		dw = pWnd->GetItemData(t); // save current data to restore it later
		txt = pWnd->GetItemText(t, _iCol); 
		pWnd->SetItemData(t, (DWORD) new CSortItem(dw, txt));
	}
}

CSortClass::~CSortClass()
{
	ASSERT(pWnd);
	int max = pWnd->GetItemCount();
	CSortItem * pItem;
	for (int t = 0; t < max; t++)
	{
		pItem = (CSortItem *) pWnd->GetItemData(t);
		ASSERT(pItem);
		pWnd->SetItemData(t, pItem->dw);
		delete pItem;
	}
}

void CSortClass::Sort(bool _bAsc, EDataType _dtype)
{
	long lParamSort = _dtype;
	
	// if lParamSort positive - ascending sort order, negative - descending
	if (!_bAsc)
		lParamSort *= -1; 
	
	pWnd->SortItems(Compare, lParamSort);
}

int CALLBACK CSortClass::Compare(LPARAM lParam1, LPARAM lParam2, LPARAM 
								 lParamSort)
{
	CSortItem * item1 = (CSortItem *) lParam1;
	CSortItem * item2 = (CSortItem *) lParam2;
	ASSERT(item1 && item2);
	
	// restore data type and sort order from lParamSort
	// if lParamSort positive - ascending sort order, negative - descending
	short   sOrder = lParamSort < 0 ? -1 : 1; 
	EDataType dType  = (EDataType) (lParamSort * sOrder); // get rid of sign
	
	// declare typed buffers
	COleDateTime t1, t2;
	
	switch (dType)
	{
	case  EDataType::dtINT:
		return (atol(item1->txt) - atol(item2->txt))*sOrder;
	case  EDataType::dtDEC:
		return (atof(item1->txt) < atof(item2->txt) ? -1 : 1)*sOrder;
	case  EDataType::dtDATETIME:
		if (t1.ParseDateTime(item1->txt) && t2.ParseDateTime(item2->txt))
			return (t1 < t2 ? -1 : 1 )*sOrder;
		else
			return 0;
	case  EDataType::dtSTRING:
		return item1->txt.CompareNoCase(item2->txt)*sOrder;
		
	default:
		ASSERT("Error: attempt to sort a column without type.");
		return 0;
	}
}


CSortClass::CSortItem::CSortItem(const DWORD _dw, const CString & _txt)
{
	dw  = _dw;
	txt = _txt;
}

==========================================================================
Here is its usage:

void CMyDlg::OnHeaderClicked(NMHDR* pNMHDR, LRESULT* pResult)
{
	static int  nSortedCol = -1;
	static bool bSortAscending = true; 
	
	HD_NOTIFY *phdn = (HD_NOTIFY *) pNMHDR;
	
	if( phdn->iButton == 0 )
	{
		// User clicked on header using left mouse button
		if( phdn->iItem == nSortedCol )
			bSortAscending = !bSortAscending;
		else
			bSortAscending = TRUE;
		
		nSortedCol = phdn->iItem;
		
		CSortClass csc(&m_List, nSortedCol);
		
		csc.Sort(bSortAscending, (CSortClass::EDataType) 
			m_arrColType[nSortedCol]); 
	}
	*pResult = 0;
}

Posted: March, 8, 98

Comments:

• Fantastic! Thanks a million! - Darshan (2003/10/20)
• OnHeaderClicked with RightMouse? - Georg Lensing (2003/09/09)
• Very good code , it's work perfect - Pavel (2003/01/08)
• Compilation Error - Jorge Santos (2002/06/04)
• Help Please!! Using this class with the ReportCtrl by Maarten Hoeben - Jamie Adams (2001/12/14)
• Extact code to get GfxListCtrl.cpp to work - Scott McCulley (2000/09/27)
• Leaving out OnGetDispInfo - Eric Schmidt (1999/12/01)
• Thanks + Question about HD_NOTIFY - Mark Sherman (1999/10/14)
• Text then Image? - Franky (1999/05/21)
• m_arrColType array - Maxim Poliashenko (1999/03/03)
• Sort list (numeric/text/float/date) using callback - Mike Albright (1999/02/26)
• Nice - Gregory Goeppel (1999/01/13)
• A word about differences from this and my article .. - Iuri Apollonio (1998/09/24)