Sorting list on Numeric Column


bool CMyListCtrl::SortNumericItems( int nCol, BOOL bAscending,int low/*=0*, int high/*=-1* )
{
	if( nCol >= ((CHeaderCtrl*)GetDlgItem(0))->GetItemCount() )
		return FALSE;
	
	if( high == -1 ) high = GetItemCount() - 1;
	int lo = low;   
	int hi = high;
	
	int midItem;
	
	if( hi <= lo ) return FALSE;
	
	midItem = atoi(GetItemText( (lo+hi)/2, nCol ));
	
	// loop through the list until indices cross
	while( lo <= hi )
	{
		// rowText will hold all column text for one row
		CStringArray rowText;
		
		// find the first element that is greater than or equal to 
		// the partition element starting from the left Index.
		if( bAscending )
			while( ( lo < high ) && (atoi(GetItemText(lo, nCol)) < midItem ) )
				++lo;           
		else
			while( ( lo < high ) && (atoi(GetItemText(lo, nCol)) > midItem ) )
				++lo;
                
		// find an element that is smaller than or equal to 
		// the partition element starting from the right Index.
		if( bAscending )
			while( ( hi > low ) && (atoi(GetItemText(hi, nCol)) > midItem ) )
				--hi;           
		else
			while( ( hi > low ) && (atoi(GetItemText(hi, nCol)) < midItem ) )
				--hi;
				
		// if the indexes have not crossed, swap                
		// and if the items are not equal
		if( lo <= hi )
		{
			// swap only if the items are not equal
			if(atoi(GetItemText(lo, nCol)) != atoi(GetItemText(hi, nCol)) )
			{                               
				// swap the rows
				LV_ITEM lvitemlo, lvitemhi;
                
				int nColCount =
							((CHeaderCtrl*)GetDlgItem(0))->GetItemCount();
				rowText.SetSize( nColCount );
                
				int i;
				for( i=0; i < nColCount; i++)
							rowText[i] = GetItemText(lo, i);
                
				lvitemlo.mask = LVIF_IMAGE | LVIF_PARAM | LVIF_STATE;
				lvitemlo.iItem = lo;
				lvitemlo.iSubItem = 0;
				lvitemlo.stateMask = LVIS_CUT | LVIS_DROPHILITED |
							LVIS_FOCUSED |  LVIS_SELECTED |
							LVIS_OVERLAYMASK | LVIS_STATEIMAGEMASK;
				lvitemhi = lvitemlo;
				lvitemhi.iItem = hi;
                
				GetItem( &lvitemlo );
				GetItem( &lvitemhi );
                
				for( i=0; i< nColCount; i++)
							SetItemText(lo, i, GetItemText(hi, i) );
                
				lvitemhi.iItem = lo;
				SetItem( &lvitemhi );
                
				for( i=0; i< nColCount; i++)
							SetItemText(hi, i, rowText[i]);
                
				lvitemlo.iItem = hi;
				SetItem( &lvitemlo );
			}
			
			++lo;
			--hi;
		}
	}
	
	// If the right index has not reached the left side of array
	// must now sort the left partition.
	if( low < hi )
		SortNumericItems( nCol, bAscending , low, hi);
	
	// If the left index has not reached the right side of array
	// must now sort the right partition.
	if( lo < high )
		SortNumericItems( nCol, bAscending , lo, high );
	
	return TRUE;
}



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