Get the next array item using the key php

Question

I have an array

Array(1=>'test',9=>'test2',16=>'test3'... and so on);

how do I get the next array item by passing the key.

for example if i have key 9 then I should get test3 as result. if i have 1 then it should return 'test2' as result.

Edited to make it More clear

echo  somefunction($array,9); //result should be 'test3'
function somefunction($array,$key)
{
  return $array[$dont know what to use];
}

Answer 1

function get_next($array, $key) {
   $currentKey = key($array);
   while ($currentKey !== null && $currentKey != $key) {
       next($array);
       $currentKey = key($array);
   }
   return next($array);
}

Or:

return current(array_slice($array, array_search($key, array_keys($array)) + 1, 1));

It is hard to return the correct result with the second method if the searched for key doesn't exist. Use with caution.