How Can I Safely Access and Handle URL Parameters in PHP?

Accessing URL Parameters in PHP

When attempting to retrieve URL parameters in PHP, it is crucial to understand that $_GET is an array that stores these parameters. To retrieve a specific parameter, simply use its key, as seen in the following example:

<?php
echo $_GET['link'];
?>

However, it is important to note that $_GET is an array, not a function or language construct. Therefore, the echo statement above will output the value of the 'link' parameter in the URL or an empty string if the parameter is not set.

To ensure your code does not trigger notices, it is recommended to check if the 'link' parameter exists using the isset() function before echoing its value:

<?php
if (isset($_GET['link'])) {
    echo $_GET['link'];
} else {
    // Fallback behavior goes here
}
?>

Alternatively, you can use the filter_input() function to retrieve and sanitize the 'link' parameter:

<?php
echo filter_input(INPUT_GET, 'link', FILTER_SANITIZE_URL);
?>

Finally, PHP 7.0 introduced the null coalescing operator (??), which allows you to handle missing parameters concisely:

<?php
echo $_GET['link'] ?? 'Fallback value';
?>

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