System.Web.UI.WebControls Namespace

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Renders a label control for displaying text on a Web page.

Label Class Members

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Constructors Visibility Constructor Parameters public Label ( )   Properties Visibility Name Value Type Accessibility public AssociatedControlID String [ Get , Set ] public SupportsDisabledAttribute Boolean [ Get ] public Text String [ Get , Set ]   Methods Visibility Name Parameters Return Type protected AddAttributesToRender ( HtmlTextWriter writer ) Void protected AddParsedSubObject ( Object obj ) Void protected LoadViewState ( Object savedState ) Void

Use the Label control to display text in a set location on the page. Unlike static text, the Text property of a label may be set programmatically, enabling you to customize the displayed text at run time.

NOTE: You can also use the Literal and PlaceHolder controls to display text on the Web Forms page. However, unlike the Label control, these controls can not render any additional elements, such as other HTML tags.

Label is particularly useful for programmatically setting text at a specified location on the page at run time, in which the text is determined dynamically, either from user input or from some other process in your code. A typical application is to display the current system date and time on a Web Form.

In certain cases, as when labels are used within templated controls, the label's Text, or a part thereof, is usually obtained dynamically from a data source.

Below is some code snippet from our sample storefront, which displays variable labels based on product specs. Each of the labels is bound to a field from a data source, the values of which are derived dynamically for each item in the DataList at run time.

<itemtemplate>
   <table cellpadding=4 width=100%>
   <tr valign = "top">
      <td width=60 align = "center">
         <asp:hyperlink id = "asinImgLink" runat = "server">
            <img id = "asinImg" runat = "server" border=0></asp:hyperlink>
      </td>
      <td>
         <asp:hyperlink id = "asinUrl" runat = "server" />
         <br>
         <asp:label id = "mfg" runat = "server" />
         <asp:label id = "seller" runat = "server" />
         <asp:label id = "release" runat = "server" />
         <asp:label id = "listprice" runat = "server" />
         <asp:label id = "ourprice" runat = "server" />
         <br>
      </td></tr>
   </table>
</itemtemplate>

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While you can set the databinding for <asp:Label> controls at design time, in the case above, databinding is done via the ItemDataBound event handler of the DataList. Below shows a snippet of that code.

void setDataBinding ( Object src, DataListItemEventArgs e ) {
   // handles the onItemDataBound event of the items datalist
   if ( e.Item.ItemType == ListItemType.Item ||
         e.Item.ItemType == ListItemType.AlternatingItem ) {

      // set reference to current data record
      DataRowView rowView = ( DataRowView ) e.Item.DataItem;
      ...

      if ( isInData ( "Manufacturer" ) ) {
         Label label = ( Label ) e.Item.FindControl ( "mfg" );
         label.Text = rowView [ "Manufacturer" ].ToString ( ) + "<br>";
      }

      // for merchants other than amazon
      if ( isInData ( "MerchantId" ) ) {
         // get and set current item's seller
         Label label = ( Label ) e.Item.FindControl ( "seller" );
         label.Text = "<i>" + ( string ) shopDb.fetchScalar
           ( "SELECT storename FROM aspx_shop_stores where merchantid='" +
               rowView [ "MerchantId" ] + "'" ) + "</i></br>";
      }

      // for books, music and videos
      if ( isInData ( "ReleaseDate" ) && ( mode == "books" || mode == "classical" ||
            mode == "dvd" || mode == "music" || mode == "vhs" ) ) {
         Label label = ( Label ) e.Item.FindControl ( "release" );
         label.Text = "<b>Release:</b> " + rowView [ "ReleaseDate" ].ToString ( ) + "<br>";
      }

      // get and set prices
      if ( isInData ( "OurPrice" ) && rowView [ "OurPrice" ].ToString ( ) != "" ) {
         string ourprice = rowView [ "OurPrice" ].ToString ( );
         Label label = ( Label ) e.Item.FindControl ( "ourprice" );
         label.Text = "<b>Our Price:</b> <b style='color:maroon'>" + ourprice + "</b>";
         if ( isInData ( "ListPrice" ) ) {
            string listprice = rowView [ "ListPrice" ].ToString ( );
            if ( string.Compare ( listprice, ourprice ) > 0 ) {
               label = ( Label ) e.Item.FindControl ( "listprice" );
               label.Text = "<b>List Price:</b> <s>" + listprice + "</s><br>";
            }
         }
      }
      ...
   }
}

For other examples illustrating use of this control, see the individual member types of this class. For syntax information, see Label in ASP.NET Syntax for Web Controls.

Literal   PlaceHolder

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