php 获取本周、本月、本年方法

/**
    * 获取本周所有日期        */        public function get_week($time = '', $format='Y-m-d'){                        $time = $time != '' ? $time : time();        //获取当前周几        $week = date('w', $time);        $date = [];        for ($i=1; $i<=7; $i++){
            $date[$i] = date($format ,strtotime($i-$week.' days',$time));                    }                        return $date;
        }

//获取本月所有日期    public function get_month(){        $j = date("t"); //获取当前月份天数        $start_time = strtotime(date('Y-m-01'));  //获取本月第一天时间戳        $array = array();        for($i=0;$i<$j;$i++){             $array[] = date('Y-m-d',$start_time+$i*86400); //每隔一天赋值给数组        }                        return $array;    }

//获取今年所有月份    public function get_years(){        $year = date('Y');        $yeararr = [];        $month = [];        for ($i=1; $i <=12 ; $i++) {            $yeararr[$i] = $year.'-'.$i;        }        foreach ($yeararr as $key => $value) {            $timestamp = strtotime( $value );            $start_time = date( 'Y-m', $timestamp );                            $month[] = $start_time;                        }                        return $month;
    }