how to define a variable global php code example

Example: How to not use directly global variables in PHP

<?php
$search_html = filter_input(INPUT_GET, 'search', FILTER_SANITIZE_SPECIAL_CHARS);
$search_url = filter_input(INPUT_GET, 'search', FILTER_SANITIZE_ENCODED);
echo "Vous avez recherché $search_html.\n";
echo "<a href='?search=$search_url'>Nouvelle recherche.</a>";
?>