XmlTextReader.HasValue Property (System.Xml)

.NET Framework Class Library

XmlTextReader..::.HasValue Property

Gets a value indicating whether the current node can have a Value other than String.Empty.

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

Syntax

Visual Basic (Declaration)

Public Overrides ReadOnly Property HasValue As Boolean

Visual Basic (Usage)

Dim instance As XmlTextReader
Dim value As Boolean

value = instance.HasValue

public override bool HasValue { get; }

Visual C++

public:
virtual property bool HasValue {
    bool get () override;
}

JScript

public override function get HasValue () : boolean

Property Value

Type: System..::.Boolean
true if the node on which the reader is currently positioned can have a Value; otherwise, false.

Remarks

Note:
In the .NET Framework version 2.0 release, the recommended practice is to create XmlReader instances using the XmlReader..::.Create method. This allows you to take full advantage of the new features introduced in this release. For more information, see Creating XML Readers.

The following table lists node types that have a value to return.

Node type	Value
Attribute	The value of the attribute.
CDATA	The content of the CDATA section.
Comment	The content of the comment.
DocumentType	The internal subset.
ProcessingInstruction	The entire content, excluding the target.
SignificantWhitespace	The white space between markup in a mixed content model.
Text	The content of the text node.
Whitespace	The white space between markup.
XmlDeclaration	The content of the declaration.

Examples

The following example displays the value for every node that can have a value.

Visual Basic

Imports System
Imports System.IO
Imports System.Xml

Public Class Sample

    Public Shared Sub Main()
        Dim reader As XmlTextReader = Nothing

        Try
            'Load the reader with the XML file.
            reader = New XmlTextReader("book1.xml")
            reader.WhitespaceHandling = WhitespaceHandling.None

            'Parse the file and display each node.
            While reader.Read()
                If reader.HasValue Then
                    Console.WriteLine("({0})  {1}={2}", reader.NodeType, reader.Name, reader.Value)
                Else
                    Console.WriteLine("({0}) {1}", reader.NodeType, reader.Name)
                End If
            End While

        Finally
            If Not (reader Is Nothing) Then
                reader.Close()
            End If
        End Try
    End Sub 'Main
End Class 'Sample

using System;
using System.IO;
using System.Xml;

public class Sample
{

  public static void Main()
  {
    XmlTextReader reader = null;

    try
    {           
        //Load the reader with the XML file.
        reader = new XmlTextReader("book1.xml");
        reader.WhitespaceHandling = WhitespaceHandling.None;

        //Parse the file and display each node.
        while (reader.Read())
        {
           if (reader.HasValue)
             Console.WriteLine("({0})  {1}={2}", reader.NodeType, reader.Name, reader.Value);
           else
             Console.WriteLine("({0}) {1}", reader.NodeType, reader.Name);
         }           
     }

     finally
     {
       if (reader!=null)
         reader.Close();
     }
  }
} // End class

Visual C++

#using <System.Xml.dll>

using namespace System;
using namespace System::IO;
using namespace System::Xml;
int main()
{
   XmlTextReader^ reader = nullptr;
   try
   {

      //Load the reader with the XML file.
      reader = gcnew XmlTextReader( "book1.xml" );
      reader->WhitespaceHandling = WhitespaceHandling::None;

      //Parse the file and display each node.
      while ( reader->Read() )
      {
         if ( reader->HasValue )
                  Console::WriteLine( "({0})  {1}={2}", reader->NodeType, reader->Name, reader->Value );
         else
                  Console::WriteLine( "({0}) {1}", reader->NodeType, reader->Name );
      }
   }
   finally
   {
      if ( reader != nullptr )
            reader->Close();
   }

}

CPP_OLD

#using <mscorlib.dll>
#using <System.Xml.dll>
using namespace System;
using namespace System::IO;
using namespace System::Xml;

int main()
{
   XmlTextReader* reader = 0;

   try
   {           
      //Load the reader with the XML file.
      reader = new XmlTextReader(S"book1.xml");
      reader->WhitespaceHandling = WhitespaceHandling::None;

      //Parse the file and display each node.
      while (reader->Read())
      {
         if (reader->HasValue)
            Console::WriteLine(S"({0})  {1}={2}", __box(reader->NodeType), reader->Name, reader->Value);
         else
            Console::WriteLine(S"({0}) {1}", __box(reader->NodeType), reader->Name);
      }           
   }

   __finally
   {
      if (reader!=0)
         reader->Close();
   }
}

The example uses the file, book1.xml, as input.

None

<?xml version='1.0' ?>
<!DOCTYPE book [<!ENTITY h 'hardcover'>]>
<book>
  <title>Pride And Prejudice</title>
  <misc>&h;</misc>
</book>

Platforms

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

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

Version Information

.NET Framework

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

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0

Reference

XmlTextReader Class

XmlTextReader Members

System.Xml Namespace

Other Resources

Reading XML with the XmlReader