C listview Example of Click Column Head Sorting

Examples are as follows:

#region  Custom variable 
  int currentCol = -1;
  bool sort;
  #endregion// Column header click event 

private void lvw_ColumnClick(object sender, ColumnClickEventArgs e)
  {
   string Asc = ((char)0x25bc).ToString().PadLeft(4, ' ');
   string Des = ((char)0x25b2).ToString().PadLeft(4, ' ');

   if (sort == false)
   {
    sort = true;
    string oldStr = this.lvw.Columns[e.Column].Text.TrimEnd((char)0x25bc, (char)0x25b2, ' ');
    this.lvw.Columns[e.Column].Text = oldStr + Des;
   }
   else if (sort == true)
   {
    sort = false;
    string oldStr = this.lvw.Columns[e.Column].Text.TrimEnd((char)0x25bc, (char)0x25b2, ' ');
    this.lvw.Columns[e.Column].Text = oldStr + Asc;
   }

   if(lvw.Columns[e.Column].Tag.ToString()=="n")// In the designer, change the column header tag Set to "n", Indicates that the column is processed as a digital comparator , Otherwise text 
    lvw.ListViewItemSorter = new ListViewItemComparerNum(e.Column, sort);
   else
    lvw.ListViewItemSorter = new ListViewItemComparer(e.Column, sort);
   this.lvw.Sort();
   int rowCount = this.lvw.Items.Count;
   if (currentCol != -1)
   {
    if (e.Column != currentCol)
     this.lvw.Columns[currentCol].Text = this.lvw.Columns[currentCol].Text.TrimEnd((char)0x25bc, (char)0x25b2, ' ');
   }
   currentCol = e.Column;
  }// Text comparator public class ListViewItemComparer : IComparer
  {
   public bool sort_b;
   public SortOrder order = SortOrder.Ascending;

   private int col;

   public ListViewItemComparer()
   {
    col = 0;
   }

   public ListViewItemComparer(int column, bool sort)
   {
    col = column;
    sort_b = sort;
   }

   public int Compare(object x, object y)
   {
    if (sort_b)
    {
     return String.Compare(((ListViewItem)x).SubItems[col].Text, ((ListViewItem)y).SubItems[col].Text);
    }
    else
    {
     return String.Compare(((ListViewItem)y).SubItems[col].Text, ((ListViewItem)x).SubItems[col].Text);
    }
   }
  }  // Digital comparator 
  public class ListViewItemComparerNum : IComparer
  {
   public bool sort_b;
   public SortOrder order = SortOrder.Ascending;

   private int col;

   public ListViewItemComparerNum()
   {
    col = 0;
   }

   public ListViewItemComparerNum(int column, bool sort)
   {
    col = column;
    sort_b = sort;
   }

   public int Compare(object x, object y)
   {
    decimal d1=Convert.ToDecimal(((ListViewItem)x).SubItems[col].Text);
    decimal d2=Convert.ToDecimal(((ListViewItem)y).SubItems[col].Text);
    if (sort_b)
    {
     return decimal.Compare(d1,d2);
    }
    else
    {
     return decimal.Compare(d2,d1);
    }
   }
  }