XPath is a language for selecting nodes in an XML document. It uses path expressions that navigate the hierarchical structure of XML. Path expressions select nodes or node-sets using steps, axes, predicates and wildcards. XPath is commonly used with XSLT to transform XML documents into other formats. It contains functions like position(), count(), and last() to retrieve information about nodes.

1. AN OVERVIEW ABOUT XPATH

2. XPATH INTRODUCTION

3. WHAT IS XPATH
 XPath is a syntax for defining parts of an XML document
 XPath uses path expressions to navigate in XML documents
 XPath contains a library of standard functions
 XPath is a major element in XSLT

4. PATH EXPRESSIONS
XPath uses path expressions to select nodes or node-sets in an XML
document.

5. XPath is Used in XSLT

6. XPath Standard Functions
number position()
Return the position of the context node among the list of nodes that
are currently being evaluated.
count()
Return the number of nodes in the argument node-set
Ej:
number count(node-set)
number last()
Return the index of the last node in the list that is currently being evaluated.

7. XPATH NODES

8. XPATH TERMINOLOGY

10. <bookstore>
<book>
<title lang="en">Harry Potter</title>
<author>J K. Rowling</author>
</book>
</bookstore>

11. RELATIONSHIP OF NODES
<history>
<year>2012</year>
<month>9</month> Children and Siblings
Parent
<day>27</day>
</history>
Parent: Each element and attribute has one parent.
Children: Element nodes may have zero, one or more children.
Siblings: Nodes that have the same parent.

12. <wiki>
<history>
<year>2012</year>
Ancestor <month>9</month> Descendants
<day>27</day>
</history>
</wiki>
Ancestors: A node's parent, parent's parent, etc.
Descendants: A node's children, children's children, etc.

13. XPATH SYNTAX

14. Selecting Nodes
XPath uses path expressions to select nodes in an XML document

15. Predicates
Predicates are used to find a specific node or a node that contains a
specific value.

16. Selecting Unknown Nodes
XPath wildcards can be used to select unknown XML elements.

17. Selecting Several Nodes
By using the | operator in an XPath expression you can select several paths.

18. XPATH AXES

19. XPath Axes
An axis defines a node-set relative to the current node.

20. LOCATION PATH EXPRESSION
A location path can be absolute or relative. An absolute location path starts with a
slash ( / ) and a relative location path does not. In both cases the location path consists
of one or more steps, each separated by a slash:
/step/step/...
step/step/...

21. Each step is evaluated against the nodes in the current node-set.
A step consists of:
an axis (defines the tree-relationship between the selected nodes and the
current node)
a node-test (identifies a node within an axis)
zero or more predicates (to further refine the selected node-set)
axisname:: nodetest [predicate]

22. EXAMPLES OF PATH EXPRESSION

23. XPATH OPERATORS

24. Below is a list of the operators that can be used in XPath expressions:

26. XPATH EXAMPLES
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