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HtmlForm Class

Provides programmatic access to the HTML <form> element on the server.

For a list of all members of this type, see HtmlForm Members.

System.Object
   System.Web.UI.Control
      System.Web.UI.HtmlControls.HtmlControl
         System.Web.UI.HtmlControls.HtmlContainerControl
            System.Web.UI.HtmlControls.HtmlForm

[Visual Basic]
Public Class HtmlForm
   Inherits HtmlContainerControl
[C#]
public class HtmlForm : HtmlContainerControl
[C++]
public __gc class HtmlForm : public HtmlContainerControl
[JScript]
public class HtmlForm extends HtmlContainerControl

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

Remarks

The HtmlForm control is a container for server controls on a Web Forms page. All server controls that post back to the server must be placed between the opening and closing tags of an HtmlForm control.

Note   ASP.NET allows only a single HtmlForm control to be placed on a Web Forms page. If you attempt to place more than one HtmlForm control a Web Forms page, the runtime will throw an System.Web.HttpException when you request the page.

You can control the behavior of the HtmlForm control by setting its properties. To specify the encoding type for the form's data, set the Enctype property. The method (Get or Post) that a browser uses to post form data to the server for processing is specified by setting the Method property.

CAUTION   By default, the Method property is set to Post. You can modify the value of this property to Get, but this may break the built-in state and post back services provided by the ASP.NET page framework.

For a list of initial property values for an instance of HtmlForm, see the HtmlForm constructor.

Example

[Visual Basic, C#] The following example demonstrates how to use the HtmlForm class to create a simple form.

[Visual Basic] 
<%@ Page Language="VB" AutoEventWireup="True" %>

<html> 

<head>

   <script runat="server">

      Protected Sub AddButton_Click(sender As Object, e As EventArgs)

         Dim Answer As Integer

         Answer = Convert.ToInt32(Value1.Value) + Convert.ToInt32(Value2.Value)

         AnswerMessage.InnerHtml = Answer.ToString()

      End Sub

   </script>

</head>

<body>

   <form Method="Post"
         Enctype="application/x-www-form-urlencoded" 
         runat="server">

      <h3> HtmlInputButton Example </h3>

      <table>

         <tr>

            <td colspan="5">

               Enter integer values into the text boxes. <br>
               Click the Add button to add the two values. <br>
               Click the Reset button to reset the text boxes.

            </td>

         </tr>

         <tr>

            <td colspan="5">

               &nbsp;

            </td>

         </tr>

         <tr align="center">

            <td>

               <input ID="Value1"
                      Type="Text"
                      Size="2"
                      MaxLength="3"
                      Value="1"
                      runat="server"/>

            </td>

            <td>

               + 

            </td>

            <td>

               <input ID="Value2"
                      Type="Text"
                      Size="2"
                      MaxLength="3"
                      Value="1"
                      runat="server"/>

            </td>

            <td>

               =

            </td>

            <td>
               
               <span ID="AnswerMessage"
                     runat="server"/>

            </td>

         </tr>

         <tr>

            <td colspan="2">

               <asp:RequiredFieldValidator
                    ID="Value1RequiredValidator"
                    ControlToValidate="Value1"
                    ErrorMessage="Please enter an value.<br>"
                    Display="Dynamic"
                    runat="server"/>

               <asp:CompareValidator
                    ID="Value1MinCompareValidator"
                    ControlToValidate="Value1"
                    Operator="LessThan"
                    Type="Integer"
                    ValueToCompare="100"
                    ErrorMessage="Please enter an integer less than 100.<br>"
                    Display="Dynamic"
                    runat="server"/>

               <asp:CompareValidator
                    ID="Value1MaxCompareValidator"
                    ControlToValidate="Value1"
                    Operator="GreaterThan"
                    Type="Integer"
                    ValueToCompare="0"
                    ErrorMessage="Please enter an integer greater than 0.<br>"
                    Display="Dynamic"
                    runat="server"/>

            </td>

            <td colspan="2">

               <asp:RequiredFieldValidator
                    ID="Value2RequiredValidator"
                    ControlToValidate="Value2"
                    ErrorMessage="Please enter an value.<br>"
                    Display="Dynamic"
                    runat="server"/>

               <asp:CompareValidator
                    ID="Value2MinCompareValidator"
                    ControlToValidate="Value2"
                    Operator="LessThan"
                    Type="Integer"
                    ValueToCompare="100"
                    ErrorMessage="Please enter an integer less than 100.<br>"
                    Display="Dynamic"
                    runat="server"/>

               <asp:CompareValidator
                    ID="Value2MaxCompareValidator"
                    ControlToValidate="Value2"
                    Operator="GreaterThan"
                    Type="Integer"
                    ValueToCompare="0"
                    ErrorMessage="Please enter an integer greater than 0.<br>"
                    Display="Dynamic"
                    runat="server"/>

            </td>

            <td>

               &nbsp
 
            </td

         </tr>

         <tr align="center">

            <td colspan="4">

               <input Type="Submit"
                      Name="AddButton
                      Value="Add"
                      OnServerClick="AddButton_Click"
                      runat="server"/>

               &nbsp;&nbsp;&nbsp;

               <input Type="Reset"
                      Name="AddButton
                      Value="Reset"
                      runat="server"/>

            </td>

            <td>

               &nbsp;

            </td>

         </tr>

      </table>

   </form>

</body>
</html>

[C#] 

<%@ Page Language="C#" AutoEventWireup="True" %>

<html> 

<head>

   <script runat="server">

      protected void AddButton_Click(Object sender, EventArgs e)
      {
         int Answer;

         Answer = Convert.ToInt32(Value1.Value) + Convert.ToInt32(Value2.Value);

         AnswerMessage.InnerHtml = Answer.ToString();

      }

   </script>

</head>

<body>

   <form Method="Post"
         Enctype="application/x-www-form-urlencoded" 
         runat="server">

      <h3> HtmlInputButton Example </h3>

      <table>

         <tr>

            <td colspan="5">

               Enter integer values into the text boxes. <br>
               Click the Add button to add the two values. <br>
               Click the Reset button to reset the text boxes.

            </td>

         </tr>

         <tr>

            <td colspan="5">

               &nbsp;

            </td>

         </tr>

         <tr align="center">

            <td>

               <input ID="Value1"
                      Type="Text"
                      Size="2"
                      MaxLength="3"
                      Value="1"
                      runat="server"/>

            </td>

            <td>

               + 

            </td>

            <td>

               <input ID="Value2"
                      Type="Text"
                      Size="2"
                      MaxLength="3"
                      Value="1"
                      runat="server"/>

            </td>

            <td>

               =

            </td>

            <td>
               
               <span ID="AnswerMessage"
                     runat="server"/>

            </td>

         </tr>

         <tr>

            <td colspan="2">

               <asp:RequiredFieldValidator
                    ID="Value1RequiredValidator"
                    ControlToValidate="Value1"
                    ErrorMessage="Please enter an value.<br>"
                    Display="Dynamic"
                    runat="server"/>

               <asp:CompareValidator
                    ID="Value1MinCompareValidator"
                    ControlToValidate="Value1"
                    Operator="LessThan"
                    Type="Integer"
                    ValueToCompare="100"
                    ErrorMessage="Please enter an integer less than 100.<br>"
                    Display="Dynamic"
                    runat="server"/>

               <asp:CompareValidator
                    ID="Value1MaxCompareValidator"
                    ControlToValidate="Value1"
                    Operator="GreaterThan"
                    Type="Integer"
                    ValueToCompare="0"
                    ErrorMessage="Please enter an integer greater than 0.<br>"
                    Display="Dynamic"
                    runat="server"/>

            </td>

            <td colspan="2">

               <asp:RequiredFieldValidator
                    ID="Value2RequiredValidator"
                    ControlToValidate="Value2"
                    ErrorMessage="Please enter an value.<br>"
                    Display="Dynamic"
                    runat="server"/>

               <asp:CompareValidator
                    ID="Value2MinCompareValidator"
                    ControlToValidate="Value2"
                    Operator="LessThan"
                    Type="Integer"
                    ValueToCompare="100"
                    ErrorMessage="Please enter an integer less than 100.<br>"
                    Display="Dynamic"
                    runat="server"/>

               <asp:CompareValidator
                    ID="Value2MaxCompareValidator"
                    ControlToValidate="Value2"
                    Operator="GreaterThan"
                    Type="Integer"
                    ValueToCompare="0"
                    ErrorMessage="Please enter an integer greater than 0.<br>"
                    Display="Dynamic"
                    runat="server"/>

            </td>

            <td>

               &nbsp
 
            </td

         </tr>

         <tr align="center">

            <td colspan="4">

               <input Type="Submit"
                      Name="AddButton
                      Value="Add"
                      OnServerClick="AddButton_Click"
                      runat="server"/>

               &nbsp;&nbsp;&nbsp;

               <input Type="Reset"
                      Name="AddButton
                      Value="Reset"
                      runat="server"/>

            </td>

            <td>

               &nbsp;

            </td>

         </tr>

      </table>

   </form>

</body>
</html>

[C++, JScript] No example is available for C++ or JScript. To view a Visual Basic or C# example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Namespace: System.Web.UI.HtmlControls

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family

Assembly: System.Web (in System.Web.dll)

See Also

HtmlForm Members | System.Web.UI.HtmlControls Namespace | HtmlContainerControl | Enctype | Method

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