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HtmlTextWriter.AddAttribute Method (String, String)

Adds the specified markup attribute and value to the opening tag of the element that the HtmlTextWriter object creates with a subsequent call to the RenderBeginTag method.

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

public virtual void AddAttribute(
	string name,
	string value


Type: System.String
A string containing the name of the attribute to add.
Type: System.String
A string containing the value to assign to the attribute.

Use the AddAttribute overload of the AddAttribute(String, String) method if the attribute is not one of the HtmlTextWriterAttribute values, or if the attribute is not known until run time.

For an instance of any given markup element, the HtmlTextWriter class maintains a list of attributes for that element. When the RenderBeginTag method is called, any attributes added by the AddAttribute method are rendered to the opening tag of the element. The list of attributes is then cleared from the HtmlTextWriter object.

The coding pattern for rendering markup elements is as follows:

  • Use the AddAttribute method to add any attributes to the element.

  • Use the RenderBeginTag method.

  • Use other methods as needed to render the content found between the element's opening and closing tags.

  • Use the RenderEndTag method.

The following code example demonstrates how to call the AddAttribute method before calling the RenderBeginTag method. The code calls two different overloads of AddAttribute and two different overloads of AddStyleAttribute before it calls the RenderBeginTag method to render a <span> element to the output stream. The AddAttribute(String, String) method is used to define the custom attribute named CustomAttribute and the custom value named CustomAttributeValue for the <span> element that this code renders.

// Set attributes and values along with attributes and styles  
// attribute defined for a <span> element.
writer.AddAttribute(HtmlTextWriterAttribute.Onclick, "alert('Hello');");
writer.AddAttribute("CustomAttribute", "CustomAttributeValue");
writer.AddStyleAttribute(HtmlTextWriterStyle.Color, "Red");
writer.AddStyleAttribute("Customstyle", "CustomStyleValue");
// Create a space and indent the markup inside the 
// <span> element.

.NET Framework

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

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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