Answer 1

If your array is always indexed consistently (eg. 'page1' is always at index '0'), it's fairly simple:

$List = array('page1', 'page2', 'page3', 'page4', 'page5');
$CurrentPage = 3; // 'page4'

while (key($List) !== $CurrentPage) next($List); // Advance until there's a match
I personally don't rely on automatic indexing because there's always a chance that the automatic index might change. You should consider explicitly defining the keys:

$List = array(
'1' => 'page1',
'2' => 'page2',
'3' => 'page3',
);
EDIT: If you want to test the values of the array (instead of the keys), use current():

while (current($List) !== $CurrentPage) next($List);