php开发中的一些常用统计的日期

<?php

echo '<br>今天:<br>';
echo date("Y-m-d",strtotime("now")), " ";
echo date("Y-m-d H:i:s",mktime(23,59,59,date("m"),date("d"),date("Y")));
echo '<br>昨天:<br>';
echo date("Y-m-d",strtotime("-1 days")), " ";
echo '<br>前天:<br>';
echo date("Y-m-d",strtotime("-2 days")), " ";
echo '<br><br>';

//echo date("Y-m-d",strtotime("+0 week Monday")), " ";
//echo date("Y-m-d",strtotime("+0 week Sunday")), " ";

//date('n') 第几个月
//date("w") 本周周几
//date("t") 本月天数

echo '<br>上周:<br>';
echo date("Y-m-d H:i:s",mktime(0, 0 , 0,date("m"),date("d")-date("w")+1-7,date("Y")))," ";
echo date("Y-m-d H:i:s",mktime(23,59,59,date("m"),date("d")-date("w")+7-7,date("Y")))," ";
echo '<br>本周:<br>';
echo date("Y-m-d H:i:s",mktime(0, 0 , 0,date("m"),date("d")-date("w")+1,date("Y")))," ";
echo date("Y-m-d H:i:s",mktime(23,59,59,date("m"),date("d")-date("w")+7,date("Y")))," ";

echo '<br>上月:<br>';
echo date("Y-m-d H:i:s",mktime(0, 0 , 0,date("m")-1,1,date("Y")))," ";
echo date("Y-m-d H:i:s",mktime(23,59,59,date("m") ,0,date("Y")))," ";
echo '<br>本月:<br>';
echo date("Y-m-d H:i:s",mktime(0, 0 , 0,date("m"),1,date("Y")))," ";
echo date("Y-m-d H:i:s",mktime(23,59,59,date("m"),date("t"),date("Y")))," ";

$getMonthDays = date("t",mktime(0, 0 , 0,date('n')+(date('n')-1)%3,1,date("Y")));//本季度未最后一月天数
echo '<br>本季度:<br>';
echo date('Y-m-d H:i:s', mktime(0, 0, 0,date('n')-(date('n')-1)%3,1,date('Y')))," ";
echo date('Y-m-d H:i:s', mktime(23,59,59,date('n')+(date('n')-1)%3,$getMonthDays,date('Y')))," ";

// $datetime=new DateTime(date('Y-m-d H:i:s'));
// $datetime->add(date_interval_create_from_date_string('1 day'));
// var_dump($datetime);
?>