PHP 随机时间

要用PHP产生随机时间 有如下代码<?function rand_time($a,$b){$a=strtotime($a);$b=strtotime($b);return date( "Y-m-d H:m:s", mt_rand($a,$b));}$date1="2010-05-10 20:03:01";$date2="2010-05-11 20:21:32";$num = 10;$i=0;while ($i < $num){ $date = rand_time($date1,$date2); $datea[]= $date; $i++;}sort($datea);$datea = array_unique($datea); //就这一句foreach ($datea as $values){echo $values."<br>";}?> 但是会输出相同的时间此外所有的时间都是相同的“分”求解决方案2010-05-10 20:05:342010-05-10 22:05:532010-05-10 23:05:252010-05-11 04:05:012010-05-11 06:05:092010-05-11 09:05:452010-05-11 10:05:172010-05-11 10:05:452010-05-11 14:05:192010-05-11 18:05:59