$city_codes = $options = array();
$city_codes['23'] = 'qwe';
$city_codes['22283'] = 'asd';
$city_codes['299'] = 'zxc';
//print_r($city_codes);
$codes_only = array_keys($city_codes);
print_r(array_keys($city_codes));
foreach ($codes_only as &$city_keyes)
print_r("∖n" . $city_codes[$city_keyes]);

//+
//php получить первый элемент ассоциативного массива

<?php

$array = array('step one', 'step two', 'step three', 'step four');

// by default, the pointer is on the first element
echo current($array) . "∖n"; // "step one"

// skip two steps
next($array);
next($array);
echo current($array) . "∖n"; // "step three"

// reset pointer, start again on step one
reset($array); // переводим указатель на первый элемент
echo current($array) . "∖n"; // "step one" = current() возвращает текущий элемент

?>