根据月份获取当月的开始日期与最后日期

//把开始时间和结束时间并转换成时间戳 默认上月的
if(empty(I('get.month'))){
$start_time = mktime(0, 0 , 0,date("m")-1,1,date("Y"));
$end_time = mktime(23,59,59,date("m") ,0,date("Y"));
}else{
$year = substr(I('get.month'),0,4);
$month = substr(I('get.month'),7,2);
$month_array = get_month($year,$month);
$start_time = $month_array['start_time'];
$end_time = $month_array['end_time'];
}

function get_month($year=0,$month =0){//这个是关键
if(empty($year) || empty($month)){
$now = time();
$year = date("Y",$now);
$month =  date("m",$now);
}
$time['start_time'] = mktime(0,0,0,$month,1,$year);
$time['end_time'] = mktime(23,59,59,($month+1),0,$year);
return $time;
}