XPathExpression Class
Provides a typed class that represents a compiled XPath expression.
Assembly: System.Xml (in System.Xml.dll)
The XPathExpression type exposes the following members.
| Name | Description | |
|---|---|---|
![]() | Expression | When overridden in a derived class, gets a string representation of the XPathExpression. |
![]() | ReturnType | When overridden in a derived class, gets the result type of the XPath expression. |
| Name | Description | |
|---|---|---|
![]() | AddSort(Object, IComparer) | When overridden in a derived class, sorts the nodes selected by the XPath expression according to the specified IComparer object. |
![]() | AddSort(Object, XmlSortOrder, XmlCaseOrder, String, XmlDataType) | When overridden in a derived class, sorts the nodes selected by the XPath expression according to the supplied parameters. |
![]() | Clone | When overridden in a derived class, returns a clone of this XPathExpression. |
![]() ![]() | Compile(String) | Compiles the XPath expression specified and returns an XPathExpression object representing the XPath expression. |
![]() ![]() | Compile(String, IXmlNamespaceResolver) | Compiles the specified XPath expression, with the IXmlNamespaceResolver object specified for namespace resolution, and returns an XPathExpression object that represents the XPath expression. |
![]() | Equals(Object) | Determines whether the specified Object is equal to the current Object. (Inherited from Object.) |
![]() | Finalize | Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.) |
![]() | GetHashCode | Serves as a hash function for a particular type. (Inherited from Object.) |
![]() | GetType | Gets the Type of the current instance. (Inherited from Object.) |
![]() | MemberwiseClone | Creates a shallow copy of the current Object. (Inherited from Object.) |
![]() | SetContext(IXmlNamespaceResolver) | When overridden in a derived class, specifies the IXmlNamespaceResolver object to use for namespace resolution. |
![]() | SetContext(XmlNamespaceManager) | When overridden in a derived class, specifies the XmlNamespaceManager object to use for namespace resolution. |
![]() | ToString | Returns a string that represents the current object. (Inherited from Object.) |
This class is returned as the result of the Compile method of the XPathNavigator class. It is a parameter to the Evaluate, Matches, Select, and SelectSingleNode methods of the XPathNavigator class.
Notes to InheritorsWhen you inherit from the XPathExpression class, you must override the following members:
The following example shows how to use the XPath return type to determine how to process the XPath expression.
public ref class Sample { public: static void Evaluate( XPathExpression^ expr, XPathNavigator^ nav ) { XPathNodeIterator^ i = nav->Select(expr); switch ( expr->ReturnType ) { case XPathResultType::Number: Console::WriteLine( nav->Evaluate( expr ) ); break; case XPathResultType::NodeSet: while ( i->MoveNext() ) Console::WriteLine( i->Current ); break; case XPathResultType::Boolean: if ( *safe_cast<bool^>(nav->Evaluate( expr )) ) Console::WriteLine( "True!" ); break; case XPathResultType::String: Console::WriteLine( nav->Evaluate( expr ) ); break; } } }; int main() { XPathDocument^ doc = gcnew XPathDocument( "contosoBooks.xml" ); XPathNavigator^ nav = doc->CreateNavigator(); XPathExpression^ expr1 = nav->Compile( ".//price/text()*10" ); // Returns a number. XPathExpression^ expr2 = nav->Compile( "bookstore/book/price" ); // Returns a nodeset. Sample^ MySample = gcnew Sample; MySample->Evaluate( expr1, nav ); MySample->Evaluate( expr2, nav ); }
The example takes the contosoBooks.xml file as input.
<?xml version="1.0" encoding="utf-8" ?>
<bookstore xmlns="http://www.contoso.com/books">
<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>
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.
