今天写程序的时候，突然发现了很早以前写的获取月份天数的函数，经典的switch版，但是获得上月天数的时候，我只是把月份-1了，估计当时太困了吧，再看到有种毛骨悚然的感觉，本来是想再处理一下的，但是一想肯定还有什么超方便的方法，于是找到了下面这个版本，做了一点小修改。
获取本月日期：
<span> <span function> getMonth(<span><span><span> <span> = <span date>("Y-m-01",<span strtotime>(<span><span><span> <span> = <span date>("Y-m-d",<span strtotime>("<span> +1 month -1 day"<span><span> <span return> <span array>(<span>,<span><span><span> }</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span>$firstday是月份的第一天，假如$date是2014-2这样的话，$firstday就会是2014-02-01，然后根据$firstday加一个月就是2014-03-01，再减一天就是2014-02-28，用date()和strtotime()真是太方便了。
获取上月日期：
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<span> <span function> getlastMonthDays(<span><span><span> <span>=<span strtotime>(<span><span><span> <span>=<span date>('Y-m-01',<span strtotime>(<span date>('Y',<span>).'-'.(<span date>('m',<span>)-1).'-01'<span><span> <span>=<span date>('Y-m-d',<span strtotime>("<span> +1 month -1 day"<span><span> <span return> <span array>(<span>,<span><span><span> }</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span>上月日期需要先获取一个时间戳，然后在月份上-1就OK了，超智能的date()会把2014-0-1这种东西转换成2013-12-01，太爽了。
获取下月日期：
<span> <span function> getNextMonthDays(<span><span><span> <span>=<span strtotime>(<span><span><span> <span>=<span getdate>(<span><span><span> <span if>(<span>['mon'] == 12<span><span> <span>=<span>['year'] +1<span><span> <span>=<span>['mon'] -11<span><span> <span>=<span>.'-0'.<span>.'-01'<span><span> <span>=<span date>('Y-m-d',<span strtotime>("<span> +1 month -1 day"<span><span> }<span else><span><span> <span>=<span date>('Y-m-01',<span strtotime>(<span date>('Y',<span>).'-'.(<span date>('m',<span>)+1).'-01'<span><span> <span>=<span date>('Y-m-d',<span strtotime>("<span> +1 month -1 day"<span><span> <span><span> <span return> <span array>(<span>,<span><span><span> }</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span>下月日期的代码看起来比较长一点，因为date()转不了类似2014-13-01这种东西，它会直接回到1970，所以前面需要处理一下12月的问题，除了12月就直接月份+1就OK啦。
总得来说，还是很方便的，日期函数太强大了。
