php语言中怎么把时间戳换成普通时间的格式显示？（具体示例）

function format_date($time){
	if(!is_numeric($time)){
		$time=strtotime($time);
	}
    $t=time()-$time;
    $f=array(
        '31536000'=>'年',
        '2592000'=>'个月',
        '604800'=>'星期',
        '86400'=>'天',
        '3600'=>'小时',
        '60'=>'分钟',
        '1'=>'秒'
    );
    foreach ($f as $k=>$v)    {
        if (0 !=$c=floor($t/(int)$k)) {
            return '<span class="pink">'.$c.' </span>'.$v.'前';
        }
    }
}

function get_last_time($time)
{
$todayLast = strtotime(date('Y-m-d 23:59:59'));
$agoTimeTrue = time() - $time;
$agoTime = $todayLast - $time;
$agoDay = floor($agoTime / 86400);
if ($agoTimeTrue < 60) {
$result = '刚刚';
} elseif ($agoTimeTrue < 3600) {
$result = (ceil($agoTimeTrue / 60)) . '分钟前';
} elseif ($agoTimeTrue < 3600 * 12) {
$result = (ceil($agoTimeTrue / 3600)) . '小时前';
} elseif ($agoDay == 1) {
$result = '昨天 ';
} elseif ($agoDay == 2) {
$result = '前天 ';
} else {
$format = date('Y') != date('Y', $time) ? "Y-m-d" : "m-d";
$result = date($format, $time);
}
return $result;
}