WriteComment Method
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XmlWriter.WriteComment Method (String)


When overridden in a derived class, writes out a comment <!--...--> containing the specified text.

Namespace:   System.Xml
Assembly:  System.Xml (in System.Xml.dll)

Public MustOverride Sub WriteComment (
	text As String


Type: System.String

Text to place inside the comment.

Exception Condition

The text would result in a non-well-formed XML document.


An XmlWriter method was called before a previous asynchronous operation finished. In this case, InvalidOperationException is thrown with the message “An asynchronous operation is already in progress.”

If text is either null or String.Empty, this method writes a comment with no data content, for example <!---->.

If text contains an invalid sequence of two dashes "--" the XmlWriter can either throw an ArgumentException (XmlTextWriter objects) or insert a space between the dashes "- -" so that the text is a valid XML comment (XmlWriter objects created by the Create method).

For the asynchronous version of this method, see WriteCommentAsync.

The following example writes an XML file representing a book.

Option Strict
Option Explicit

Imports System
Imports System.IO
Imports System.Xml

Public Class Sample
    Private Const filename As String = "sampledata.xml"

  Public Shared Sub Main()

     Dim settings As XmlWriterSettings = new XmlWriterSettings()
     settings.Indent = true
     Dim writer As XmlWriter = XmlWriter.Create(filename, settings)

     ' Write the Processing Instruction node.
     Dim PItext As String = "type=""text/xsl"" href=""book.xsl"""
     writer.WriteProcessingInstruction("xml-stylesheet", PItext)

     'Write the DocumentType node.
     writer.WriteDocType("book", Nothing, Nothing, "<!ENTITY h ""hardcover"">")

     ' Write a Comment node.
     writer.WriteComment("sample XML")

     ' Write the root element.

     ' Write the genre attribute
     writer.WriteAttributeString("genre", "novel")

     ' Write the ISBN attribute.
     writer.WriteAttributeString("ISBN", "1-8630-014")

     ' Write the title.
     writer.WriteElementString("title", "The Handmaid's Tale")

     ' Write the style element.

     ' Write the price.
     writer.WriteElementString("price", "19.95")

     ' Write CDATA.
     writer.WriteCData("Prices 15% off!!")

     ' Write the close tag for the root element.


     ' Write the XML to file and close the writer

    End Sub 'Main 
End Class 'Sample

Universal Windows Platform
Available since 4.5
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
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