PHP 8 Programming Tips, Tricks, and Best Practices/

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Nullsafe Operator

Nullsafe Operator

Learn about the nullsafe operator and how it provides the ability to handle the NULL data type.

We'll cover the following...

The nullsafe operator is used in a chain of object property references. If one of the properties in the chain does not exist (in other words, it is considered NULL), the operator returns a value of NULL safely without issuing a warning.

In our example, we must have the following:

  • An Extended Markup Language (XML) file named produce.xml.

  • Lines 4–15: We also need to define a getQuantity() function that first checks to see if that property is not empty before proceeding to the next level.

  • Lines 18–30: A code snippet that scans through the XML document and displays quantities.

<?php
// Define the getQuantity() function 
function getQuantity(SimpleXMLElement $xml, string $type, string $item)
{
	$qty = 0;
	if (!empty($xml->dept)) {
		if (!empty($xml->dept->$type)) {
			if (!empty($xml->dept->$type->$item)) {
				$qty = $xml->dept->$type->$item;
			}
		}
	}
	return $qty;
}

// Load the XML file
$xml = simplexml_load_file(__DIR__ . '/produce.xml');

// Define the produce array with types and items
$produce = [
	'fruit' => ['apple','banana','cherry','pear'],
	'vegetable' => ['artichoke','beans','cabbage','squash']
];

$pattern = "%10s : %d\n"; // Pattern for displaying item and quantity

// Iterate over each type of produce
foreach ($produce as $type => $items) {
	echo ucfirst($type) . ":\n"; // Print the type (capitalized)

	// Iterate over each item in the produce type
	foreach ($items as $item) {
		$qty = getQuantity($xml, $type, $item); // Get the quantity for the item
		printf($pattern, $item, $qty); // Print the item and quantity using the pattern
	}
}
?>
Displaying array elements with a combination of XML files using nested If statements in PHP 7

As we start dealing with deeper nesting levels, the function ...