根据日期来判断还剩余几天,并作出今天明天后天的判断

if($catid==77)
{

$days= diffBetweenTwoDays($vo['riqi'],date("y-m-d",time()));
if($days==0)echo "今天";
elseif($days==1)echo "明天";
elseif($days==2)echo "后天";
else echo $days."天";

}elseif($catid==78)
{
     echo "过期";    
}

diffBetweenTwoDays：参考“求两个日期之间相差的天数”