- filter_input: documentation ( source)
- sprintf: documentation ( source)
<?php
$options = [
'default' => 0,
'min_range' => 0,
'max_range' => 999,
];
$id = filter_input(INPUT_GET, 'id', FILTER_SANITIZE_NUMBER_INT, ['options' => $options]);
$link = sprintf('https://www.stronka.pl/index.php?id=%d', $id);
echo '<a href="'. $link .'"><img src="https://www.stronka.pl/button.png"></a>';