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DataGridColumnCollection.Clear Method

Removes all DataGridColumn-derived column objects from the DataGridColumnCollection collection.

Namespace:  System.Web.UI.WebControls
Assembly:  System.Web (in System.Web.dll)

public void Clear()

Use this method to remove all DataGridColumn-derived column objects from the DataGridColumnCollection collection.

NoteNote

The Count property is automatically set to 0 after this method is used.

The following code example demonstrates how to use the Clear method to empty the DataGridColumnCollection collection before adding new columns to the collection.

<%@ Page Language="C#" AutoEventWireup="True" %>
<%@ Import Namespace="System.Data" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
   <script language="C#" runat="server">

      ICollection CreateDataSource() 
      {
         DataTable dt = new DataTable();
         DataRow dr;

         dt.Columns.Add(new DataColumn("IntegerValue", typeof(Int32)));
         dt.Columns.Add(new DataColumn("StringValue", typeof(string)));
         dt.Columns.Add(new DataColumn("CurrencyValue", typeof(double)));

         for (int i = 0; i < 9; i++) 
         {
            dr = dt.NewRow();

            dr[0] = i;
            dr[1] = "Item " + i.ToString();
            dr[2] = 1.23 * (i + 1);

            dt.Rows.Add(dr);
         }

         DataView dv = new DataView(dt);
         return dv;
      }

      void Page_Init(Object sender, EventArgs e) 
      {

         // Empty DataGridColumnsCollection collection. 
         ItemsGrid.Columns.Clear();

         // Create dynamic columns to add to Columns collection.
         BoundColumn IntegerColumn = new BoundColumn();
         BoundColumn StringColumn = new BoundColumn();
         BoundColumn PriceColumn = new BoundColumn();

         IntegerColumn.HeaderText="Item Number"; 
         IntegerColumn.DataField="IntegerValue";

         StringColumn.HeaderText="Item"; 
         StringColumn.DataField="StringValue";

         PriceColumn.HeaderText="Price"; 
         PriceColumn.DataField="CurrencyValue";

         // Add columns to Columns collection.
         ItemsGrid.Columns.Add(IntegerColumn);
         ItemsGrid.Columns.Add(StringColumn);
         ItemsGrid.Columns.Add(PriceColumn);

      } 

      void Page_Load(Object sender, EventArgs e) 
      {

         if (!IsPostBack) 
         {
            // Load this data only once.
            ItemsGrid.DataSource= CreateDataSource();
            ItemsGrid.DataBind();
         }

      }

   </script>

<head runat="server">
    <title>DataGridColumnCollection Clear Example</title>
</head>
<body>

   <form id="form1" runat="server">

      <h3>DataGridColumnCollection Clear Example</h3>

      <b>Product List</b>

      <asp:DataGrid id="ItemsGrid"
           BorderColor="black"
           BorderWidth="1"
           CellPadding="3"
           AutoGenerateColumns="false"
           runat="server">

         <HeaderStyle BackColor="#00aaaa">
         </HeaderStyle>

         <Columns>

            <asp:BoundColumn 
                 HeaderText="Item Number" 
                 DataField="IntegerValue"/>

            <asp:BoundColumn 
                 HeaderText="Item" 
                 DataField="StringValue"/>

            <asp:BoundColumn 
                 HeaderText="Price" 
                 DataField="CurrencyValue" 
                 DataFormatString="{0:c}">

               <ItemStyle HorizontalAlign="right">
               </ItemStyle>

            </asp:BoundColumn>

         </Columns>

      </asp:DataGrid>    

   </form>

</body>
</html>

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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