/**

* 取得隨機數

*

* @param int $length 生成隨機數的長度

* @param int $numeric 是否只產生數字隨機數 1是0否

* @return string

*/

function random($length, $numeric = 0) {

$seed = base_convert(md5(microtime().$_SERVER['DOCUMENT_ROOT']), 16, $numeric ? 10 : 35);

$seed = $numeric ? (str_replace('0', '', $seed).'012340567890') : ($seed.'zZ'.strtoupper($seed));

$hash = '';

$max = strlen($seed) - 1;

for($i = 0; $i < $length; $i++) {

$hash .= $seed{mt_rand(0, $max)};

}

return $hash;

}