How to set an Arrays internal pointer to a specific position? PHP/XML

Question

Im trying to build a little site using XML instead of a database.

I would like to build a next and prev button which will work relative to the content I have displayed.

I found the php function next() and prev() as well as current() but I do not know how to set the pointer to a specific position to be able to navigate relative to the current page.

$list=array('page1','page2','page3') 

eg if im displaying contents of page2 how could I tell php i am at $list[1] so that next($list) shows page3?

Thanks in advance

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); 

Answer 2

Using the functions below, you can get the next and previous values of the array. If current value is not valid or it is the last (first - for prev) value in the array, then:

• the function getNextVal(...) returns the first element value
• the function getPrevVal(...) returns the last element value

The functions are cyclic.

function getNextVal(&$array, $curr_val) {     $next = 0;     reset($array);      do     {         $tmp_val = current($array);         $res = next($array);     } while ( ($tmp_val != $curr_val) && $res );      if( $res )     {         $next = current($array);     }      return $next; }  function getPrevVal(&$array, $curr_val) {     end($array);     $prev = current($array);      do     {         $tmp_val = current($array);         $res = prev($array);     } while ( ($tmp_val != $curr_val) && $res );      if( $res )     {         $prev = current($array);     }      return $prev; }