格式化时间的函数

//格式化时间
function time_format($time, $start='d', $keep='s', $unit=true){

$day = $hours = $minutes = $seconds = '';
if($start == 'd'){
//$time / 3600 得到小时数,再除以24小时,余数则为不足一天的小时数
$day = floor($time / 3600 / 24);
$hours = floor($time / 3600) % 24;
$minutes = floor($time / 60) % 60;
$seconds = $time % 60;
}elseif($start == 'h'){
$hours = floor($time / 3600);
$minutes = floor($time / 60) % 60;
$seconds = $time % 60;
}elseif($start == 'i'){
$minutes = floor($time / 60);
$seconds = $time % 60;
}

//如果要带单位
if($unit){
$day = ($day)? $day.'天' : '';
$hours = ($hours)? $hours.'小时' : '';
$minutes = ($minutes)? $minutes.'分钟' : '';
$seconds = ($seconds)? $seconds.'秒' : '';
}

$new['d'] = $day;
$new['h'] = $hours;
$new['i'] = $minutes;
$new['s'] = $seconds;

$time = '';
foreach($new as $key => $val){
if($key == $start) $go = true;
if($go){
if($unit){
$time .= $val;
}else{
$time[$key]= $val;
}
}
if($key == $keep) break;
}
return $time;
}