1. strtotime
date("Y-m-d",strtotime(‘+1day‘))
2. mktime
date("Y-m-d",mktime(0,0,0,date(‘m‘),date(‘d‘)+1))
3. time
time() + (7 * 24 * 60 * 60) // 7 days; 24 hours; 60 mins; 60 secs
// 7 days; 24 hours; 60 mins; 60 secs
php改变时间的方法
原文：http://www.cnblogs.com/yaohunzhanyue/p/7488747.html
