Form:
<form action="script.php" method="POST">
<input name="variable" value="lost and found"><br>
lost: <input name="array[lost]" value="lost and found"><br>
'lost': <input name="array['lost']" value="lost and found"><br>
long key: <input name="array[testoflongkey]" value="lost and found"><br>
<input type="submit"><br>
</form>

script.php:
<?PHP
print_r ($_POST);
?>

When the form is submited (with "lost and found" string as input value) the following output is displayed:

Array
(
    [variable] => lost and found
    [array] => Array
        (
            [lost] =>  and found
            ['lost'] =>  found
            [testoflongkey] =>  and found
        )

)

As you can see there are characters missing in result array.