XML XPath Operators Overview
The following are the XPath operators that are used to manipulate and compare the data in XML documents
Syntax
Arithmetic Operators
| Operator | Description |
|---|---|
| + | Addition |
| - | Subtraction |
| * | Multiplication |
| div | Division |
| mod | Remainder |
Comparison Operators
| Operator | Description |
|---|---|
| = | Equal |
| != | Not Equal |
| < | Less Than |
| > | Greater Than |
| <= | Less Than or Equal |
| >= | Greater Than or Equal |
Logical Operators
| Operator | Description |
|---|---|
| and | Logical AND |
| or | Logical OR |
| not | Logical NOT |
Example
Here's an example XPath expression that utilizes a few of the XPath operators:
//bookstore/book[price > 20 and @category = 'fiction']
In this example, we're selecting all the book elements that have a price greater than 20 and whose category attribute equals "fiction".
Output
The output of an XPath expression that uses operators will depend on the specific expression and the structure of the XML document being queried.
In the example expression above, the output would include all the book elements that meet the conditions specified in the predicate.
Explanation
XPath operators are used to compare data in XML documents and manipulate the results of XPath expressions.
The arithmetic operators (+, -, *, div, mod) can be used to perform basic math on numeric data in the document.
The comparison operators (=, !=, <, >, <=, >=) are used to compare nodes and node values in the document.
Logical operators (and, or, not) are used to combine two or more conditions in an XPath expression.
Use
XPath operators are used to refine the results of XPath expressions, to select specific portions of XML documents based on certain criteria, and to manipulate the data contained within those documents.
For example, you might use XPath operators to:
- Select all elements in an XML document that have a certain attribute and value.
- Filter out elements from the results of a larger XPath expression based on a certain criterion.
- Calculate the average, sum, or other mathematical aggregate of a certain subset of elements in an XML document.
Important Points
- XPath operators are essential tools for querying, filtering, and manipulating data in XML documents.
- It's important to understand which operator to use in order to achieve the desired results when working with XPath expressions.
- Often, XPath expressions will combine multiple operators in order to achieve more complex queries or calculations.
Summary
XPath operators are essential elements of XPath expressions that allow you to compare, filter, and manipulate the data in XML documents. By understanding the various arithmetic, comparison, and logical operators available in XPath, you can craft powerful expressions that extract the precise information you need from your documents.