今天在使用slimstat的时候发现，当在fitler中选择某一天当情况下，Summary的title就变成了“compare with%s”,应该出现的2个日期全部见了。
还以为是slimstat的bug。debug了一下发现，应该传递的参数都正常。只是返回的格式化日期为空。slimstat格式化日期的方法为：gmstrftime("%a %e %b %Y", gmmktime(12, 0, 0, $mo, $dy, $yr));debug这个方法才知道，只要有%e这个参数，gmstrftime就返回了空字符串。查看了php manual看到下面那段话，
Not all conversion specifiers may be supported by your C library, in which case they will not be supported by PHP's strftime(). Additionally, not all platforms support negative timestamps, so your date range may be limited to no earlier than the Unix epoch. This means that %e, %T, %R and, %D (and possibly others) - as well as dates prior to Jan 1, 1970 - will not work on Windows, some Linux distributions, and a few other operating systems. For Windows systems, a complete overview of supported conversion specifiers can be found at » MSDN
看样子php manual还是需要好好的研究研究。