C# - HtmlTextWriter Example

HtmlTextWriter writes HTML. It allows you to generate a list of HTML elements, such as div elements. You could use StringBuilder, but HtmlTextWriter is sometimes better.

Notes, HTML. It is easy to generate HTML using StringBuilder, just like any other string. That approach can result in complex syntax and syntax errors.

StringBuilder

String Remove HTML

HtmlEncode, HtmlDecode

Example. First, the HtmlTextWriter class is found in the System.Web.UI namespace. You may need to reference the System.Web assembly. You also need the System.IO namespace for StringWriter.

Detail The new StringWriter is required for the HtmlTextWriter to write to. It is a buffer and everything that is written is written to this.

StringWriter

Detail We need to use "RenderBegin" and "RenderEnd" methods. Call RenderBeginTag to open a new level in the HTML with that tag.

And You must manually close that level of that markup with RenderEndTag. These 2 methods must be called in pairs.

Detail Add the attribute with AddAttribute before BeginRenderTag. Look for "HtmlTextWriterAttribute.Class" and similar.

using System; using System.IO; using System.Web.UI; class Program { static string[] _words = { "Sam", "Dot", "Perls" }; static string GetDivElements() { // Initialize StringWriter instance. StringWriter stringWriter = new StringWriter(); // Put HtmlTextWriter in using block because it needs to call Dispose. using (HtmlTextWriter writer = new HtmlTextWriter(stringWriter)) { // Loop over some strings. foreach (var word in _words) { // Some strings for the attributes. string classValue = "ClassName"; string urlValue = "http://www.dotnetperls.com/"; string imageValue = "image.jpg"; // The important part: writer.AddAttribute(HtmlTextWriterAttribute.Class, classValue); writer.RenderBeginTag(HtmlTextWriterTag.Div); // Begin #1 writer.AddAttribute(HtmlTextWriterAttribute.Href, urlValue); writer.RenderBeginTag(HtmlTextWriterTag.A); // Begin #2 writer.AddAttribute(HtmlTextWriterAttribute.Src, imageValue); writer.AddAttribute(HtmlTextWriterAttribute.Width, "60"); writer.AddAttribute(HtmlTextWriterAttribute.Height, "60"); writer.AddAttribute(HtmlTextWriterAttribute.Alt, ""); writer.RenderBeginTag(HtmlTextWriterTag.Img); // Begin #3 writer.RenderEndTag(); // End #3 writer.Write(word); writer.RenderEndTag(); // End #2 writer.RenderEndTag(); // End #1 } } // Return the result. return stringWriter.ToString(); } static void Main() { // Demonstrate HtmlTextWriter. Console.WriteLine(GetDivElements()); } }

<div class="ClassName"> <a href="http://www.dotnetperls.com/"> <img src="image.jpg" width="60" height="60" alt="" />Sam</a> </div><div class="ClassName"> <a href="http://www.dotnetperls.com/"> <img src="image.jpg" width="60" height="60" alt="" />Dot</a> </div><div class="ClassName"> <a href="http://www.dotnetperls.com/"> <img src="image.jpg" width="60" height="60" alt="" />Perls</a> </div>

Tab string. In the constructor to the HtmlTextWriter, use an empty string as the tab string. This will eliminate a lot of whitespace—it can reduce page size.

string.Empty

using (HtmlTextWriter writer = new HtmlTextWriter(stringWriter, string.Empty)) { // Insert code here. }

Notes, tags. In the code, every tag is started and then closed later. The Write() method is an instance method that writes text in between the tags in HTML.

XmlWriter. Using XmlWriter is similar, but the output is XML. This is useful for interoperability and settings files. HtmlTextWriter is mainly useful for web pages in ASP.NET.

XmlWriter

A summary. We used the HtmlTextWriter class in the System.Web namespace. Use HtmlTextWriter to write HTML instead of StringBuilder alone for the cleanest and object-oriented code.