Question

How can I use next() to traverse the array like this in PHP:

$a = array(NULL=>NULL, FALSE=>FALSE)

This kind of code will not work:

reset($a);
while (key($a)) {
    print "a";
    next($a);
}

Answer 1

If you check the manual of next(), you will see this.

You won’t be able to distinguish the end of an array from a boolean
FALSE element. To properly traverse an array which may contain FALSE
elements, see the each() function.

Here is a workaround:

$fruit = array('a' => 'apple', 'b' => 'banana', 'c' => 'cranberry');

reset($fruit);
while (list($key, $val) = each($fruit)) {
    echo "$key => $val<br>";
}

You could also try foreach.

$fruit = array('a' => 'apple', 'b' => 'banana', 'c' => 'cranberry');
foreach($fruit as $key => $val){
    echo "$key => $val<br>";
}