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XPathNodeIterator Class

Provides an iterator over a selected set of nodes.

System.Object
  System.Xml.XPath.XPathNodeIterator

Namespace:  System.Xml.XPath
Assembly:  System.Xml (in System.Xml.dll)
public abstract class XPathNodeIterator : ICloneable, 
	IEnumerable

The XPathNodeIterator type exposes the following members.

  NameDescription
Protected methodXPathNodeIteratorInitializes a new instance of the XPathNodeIterator class.
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  NameDescription
Public propertyCountGets the index of the last node in the selected set of nodes.
Public propertyCurrentWhen overridden in a derived class, gets the XPathNavigator object for this XPathNodeIterator, positioned on the current context node.
Public propertyCurrentPositionWhen overridden in a derived class, gets the index of the current position in the selected set of nodes.
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  NameDescription
Public methodCloneWhen overridden in a derived class, returns a clone of this XPathNodeIterator object.
Public methodEquals(Object)Determines whether the specified object is equal to the current object. (Inherited from Object.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodGetEnumeratorReturns an IEnumerator object to iterate through the selected node set.
Public methodGetHashCodeServes as the default hash function. (Inherited from Object.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodMoveNextWhen overridden in a derived class, moves the XPathNavigator object returned by the Current property to the next node in the selected node set.
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
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  NameDescription
Public Extension MethodAsParallelEnables parallelization of a query. (Defined by ParallelEnumerable.)
Public Extension MethodAsQueryableConverts an IEnumerable to an IQueryable. (Defined by Queryable.)
Public Extension MethodCast<TResult>Casts the elements of an IEnumerable to the specified type. (Defined by Enumerable.)
Public Extension MethodOfType<TResult>Filters the elements of an IEnumerable based on a specified type. (Defined by Enumerable.)
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  NameDescription
Explicit interface implemetationPrivate methodICloneable.CloneCreates a new object that is a copy of the current instance.
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An XPathNodeIterator object returned by the XPathNavigator class is not positioned on the first node in a selected set of nodes. A call to the MoveNext method of the XPathNodeIterator class must be made to position the XPathNodeIterator object on the first node in the selected set of nodes.

When using the XPathNodeIterator, if you edit the current node or any of its ancestors, your current position is lost. If you want to edit a number of nodes that you have selected, create a XPathNavigator array, copy all of the nodes from the XPathNodeIterator into the array, then iterate through the array and modify the nodes.

There are two ways to iterate over an XPathNavigator collection by using the XPathNodeIterator class.

One way is to use the MoveNext method and then call Current to get the current XPathNavigator instance, as in the following example:

while (nodeIterator.MoveNext())
{
    XPathNavigator n = nodeIterator.Current;
    Console.WriteLine(n.LocalName);
}

Another way is to use a foreach loop to call the GetEnumerator method and use the returned IEnumerator interface to enumerate the nodes, as in the following example:

foreach (XPathNavigator n in nodeIterator)
    Console.WriteLine(n.LocalName);

You should either use MoveNext and Current or use GetEnumerator. Combining these two approaches can cause unexpected results. For example, if the MoveNext method is called first, and then the GetEnumerator method is called in the foreach loop, the foreach loop will not start enumerating the results from the beginning of the collection, but from the position after the Current method.

Notes to Inheritors

When you inherit from the XPathNodeIterator class, you must override the following members:

The following example uses the Select method of the XPathNavigator class to select a node set using the XPathNodeIterator class.

XPathDocument document = new XPathDocument("books.xml");
XPathNavigator navigator = document.CreateNavigator();

XPathNodeIterator nodes = navigator.Select("/bookstore/book");
nodes.MoveNext();
XPathNavigator nodesNavigator = nodes.Current;

XPathNodeIterator nodesText = nodesNavigator.SelectDescendants(XPathNodeType.Text, false);

while (nodesText.MoveNext())
    Console.WriteLine(nodesText.Current.Value);

The example takes the books.xml file as input.

<?xml version="1.0" encoding="utf-8" ?> 
<bookstore>
    <book genre="autobiography" publicationdate="1981-03-22" ISBN="1-861003-11-0">
        <title>The Autobiography of Benjamin Franklin</title>
        <author>
            <first-name>Benjamin</first-name>
            <last-name>Franklin</last-name>
        </author>
        <price>8.99</price>
    </book>
    <book genre="novel" publicationdate="1967-11-17" ISBN="0-201-63361-2">
        <title>The Confidence Man</title>
        <author>
            <first-name>Herman</first-name>
            <last-name>Melville</last-name>
        </author>
        <price>11.99</price>
    </book>
    <book genre="philosophy" publicationdate="1991-02-15" ISBN="1-861001-57-6">
        <title>The Gorgias</title>
        <author>
            <name>Plato</name>
        </author>
        <price>9.99</price>
    </book>
</bookstore>

.NET Framework

Supported in: 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

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