2个自定义的PHP in_array 函数，解决大量数据判断in_array的效率问题

/**
 * in_array is too slow when array is large
 */
public static function inArray($item, $array) {
    $flipArray = array_flip($array);
    return isset($flipArray[$item]);
}

<?php
$search_array = array(&#39;first&#39; => null, &#39;second&#39; => 4);
// returns false
isset($search_array[&#39;first&#39;]);
// returns true
array_key_exists(&#39;first&#39;, $search_array);
?>

/**
 * in_array is too slow when array is large
 */
public static function inArray($item, $array) {
    $str = implode(',', $array);
    $str = ',' . $str . ',';
    $item = ',' . $item . ',';
    return false !== strpos($item, $str) ? true : false;
}