php时间,time()和date()
time():
Returns the current time measured in the number of seconds since the Unix Epoch (January 1 1970 00:00:00 GMT).
意思返回从unix纪元到现在的秒数
date():
string date($string format [, int timestamp = time() ])
第一个是格式,第二个是秒数,默认是time()函数返回的数字。