数组辅助函数
数组辅助函数的文件涵盖了一些用于辅助数组操作的函数。
装载本辅助函数
本辅助函数的装载通过如下代码完成：
$this->load->helper('array');
可用的函数如下：
element()
获取数组中的元素。本函数测试数组的索引是否已设定并含有数值。如果已设有数值则返回该数值，否则返回 FALSE，或任何你设定的默认数值（函数第三个参数）。范例：
$array = array('color' => 'red', 'shape' => 'round', 'size' => '');
// 返回 "red"
echo element('color', $array);
// 返回 NULL
echo element('size', $array, NULL);
random_element()
根据提供的数组，随机返回该数组内的一个元素。使用范例：
$quotes = array(
"I find that the harder I work, the more luck I seem to have. - Thomas Jefferson",
"Don't stay in bed, unless you can make money in bed. - George Burns",
"We didn't lose the game; we just ran out of time. - Vince Lombardi",
"If everything seems under control, you're not going fast enough. - Mario Andretti",
"Reality is merely an illusion, albeit a very persistent one. - Albert Einstein",
"Chance favors the prepared mind - Louis Pasteur"
);
echo random_element($quotes);
