How to convert XML document to array in PHP

In the PHP development process, XML processing is a very common operation, and PHP provides many functions and class libraries for XML processing. Among them, the function of converting XML documents into PHP arrays is a very important operation, because it can easily use XML data for subsequent operations and logical analysis. This article will discuss some commonly used functions in PHP for converting XML documents into PHP arrays.

1. simplexml_load_string()

simplexml_load_string() is a commonly used function in PHP, which can convert XML documents into simple XML objects in PHP. This function receives an XML document as a string and creates a simple XML object by parsing the document. The following is a simple example:

$xml_string = "<students><student><name>Tom</name><age>18</age></student></students>";
$xml_object = simplexml_load_string($xml_string);
print_r($xml_object);

The above code will output the following results:

SimpleXMLElement Object
(
    [student] => SimpleXMLElement Object
        (
            [name] => Tom
            [age] => 18
        )
)

In the above example, we use an XML string as a parameter of the simplexml_load_string() function, and Assign the returned object to the $xml_object variable. We found that the value of $xml_object is a SimpleXMLElement object, which contains all the data in the XML document.

It should be noted that the simplexml_load_string() function is usually used for simple XML document processing. If your XML document is more complex, it is recommended to use other XML processing functions and class libraries.

2. simplexml_load_file()

The simplexml_load_file() function is very similar to the simplexml_load_string() function. The only difference is that the former parses the XML document from the PHP file system. The following is a simple example:

$xml_file = "students.xml";
$xml_object = simplexml_load_file($xml_file);
print_r($xml_object);

The above code will output the following results:

SimpleXMLElement Object
(
    [student] => Array
        (
            [0] => SimpleXMLElement Object
                (
                    [name] => Tom
                    [age] => 18
                )
        )
)

In the above example, we use the simplexml_load_file() function to parse an XML file into a SimpleXMLElement object And assign it to the $xml_object variable. This function facilitates parsing XML files from the file system, but you also need to be aware of the complexity of XML files.

3. xml_parse_into_struct()

xml_parse_into_struct() function is a very commonly used function in PHP, which can parse XML documents into PHP arrays. Different from the simplexml_load_string() function and simplexml_load_file() function, the xml_parse_into_struct() function returns a two-dimensional array that contains all elements and attributes in the XML document. The following is a simple example:

$xml_string = "<students><student><name>Tom</name><age>18</age></student></students>";
$xml_parser = xml_parser_create();
xml_parse_into_struct($xml_parser, $xml_string, $xml_array);
xml_parser_free($xml_parser);
print_r($xml_array);

The above code will output the following results:

Array
(
    [0] => Array
        (
            [tag] => students
            [type] => open
            [level] => 1
        )

    [1] => Array
        (
            [tag] => student
            [type] => open
            [level] => 2
        )

    [2] => Array
        (
            [tag] => name
            [type] => complete
            [level] => 3
            [value] => Tom
        )

    [3] => Array
        (
            [tag] => age
            [type] => complete
            [level] => 3
            [value] => 18
        )

    [4] => Array
        (
            [tag] => student
            [type] => close
            [level] => 2
        )

    [5] => Array
        (
            [tag] => students
            [type] => close
            [level] => 1
        )
)

In the above example, we use the xml_parser_create() function to create an XML parser, and then use The xml_parse_into_struct() function parses an XML string into a PHP array and assigns it to the $xml_array variable. Finally, we use the print_r() function to output the value of the $xml_array array.

It should be noted that the xml_parse_into_struct() function is only suitable for parsing small XML documents. For large and complex XML documents, it is recommended to use other XML parsing functions or libraries.

4. DOMDocument class

The DOMDocument class is a very commonly used and powerful XML parser in PHP. It can parse XML documents into DOM objects and provides a set of APIs to access and modify the nodes and properties of this object. The following is a simple example:

$xml_string = "<students><student><name>Tom</name><age>18</age></student></students>";
$dom_document = new DOMDocument();
$dom_document->loadXML($xml_string);
$students = $dom_document->getElementsByTagName('student');
foreach ($students as $student) {
    $name = $student->getElementsByTagName('name')->item(0)->nodeValue;
    $age = $student->getElementsByTagName('age')->item(0)->nodeValue;
    echo "Name: $name, Age: $age";
}

The above code will output the following results:

Name: Tom, Age: 18

In the above example, we use the DOMDocument class to parse the XML string into a DOM object, and use The getElementsByTagName() function selects the student node. Finally, we use the nodeValue property to get the value of the node and output it to the screen.

It should be noted that the DOMDocument class provides a wealth of methods and attributes for operating and modifying XML documents, making it the best choice for XML parsing and processing.

Summary

In this article, we have introduced in detail some common functions and class libraries in PHP for converting XML documents into PHP arrays. These functions and class libraries can easily use XML data for subsequent operations and logical analysis. In actual use, depending on the complexity of the XML document and the usage scenarios, we can choose different functions and class libraries to complete our XML processing tasks.

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