<?php     echo "<pre>";  echo date("Y-m-d",strtotime("now")), "\n";  echo "<pre>";  echo date("Y-m-d",strtotime("-1 week Monday")), "\n";  echo "<pre>";  echo date("Y-m-d",strtotime("-1 week Sunday")), "\n";  echo "<pre>";  echo date("Y-m-d",strtotime("+0 week Monday")), "\n";  echo "<pre>";  echo date("Y-m-d",strtotime("+0 week Sunday")), "\n";  echo "<pre>";     echo "*********第几个月:";  echo date('n');   echo "<pre>";  echo "*********本周周几:";  echo date("w");   echo "<pre>";  echo "*********本月天数:";  echo date("t");     echo "<pre>";     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"))),"\n";  echo date("Y-m-d H:i:s",mktime(23,59,59,date("m"),date("d")-date("w")+7-7,date("Y"))),"\n";  echo "<pre>";  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"))),"\n";  echo date("Y-m-d H:i:s",mktime(23,59,59,date("m"),date("d")-date("w")+7,date("Y"))),"\n";  echo "<pre>";  echo '<br>上上月:<br>';  echo date("Y-m-d H:i:s",mktime(0, 0 , 0,date("m")-2,1,date("Y"))),"\n";  echo date("Y-m-d H:i:s",mktime(23,59,59,date("m")-1,0,date("Y"))),"\n";  echo "<pre>";     echo '<br>上月:<br>';  echo date("Y-m-d H:i:s",mktime(0, 0 , 0,date("m")-1,1,date("Y"))),"\n";  echo date("Y-m-d H:i:s",mktime(23,59,59,date("m") ,0,date("Y"))),"\n";  echo "<pre>";  echo '<br>本月:<br>';  echo date("Y-m-d H:i:s",mktime(0, 0 , 0,date("m"),1,date("Y"))),"\n";  echo date("Y-m-d H:i:s",mktime(23,59,59,date("m"),date("t"),date("Y"))),"\n";  echo "<pre>";      echo "<pre>";  $season = ceil((date('n'))/3)-2;//上季度是第几季度  echo '<br>上上季度:<br>';  echo date('Y-m-d H:i:s', mktime(0, 0, 0,$season*3-3+1,1,date('Y'))),"\n";  echo date('Y-m-d H:i:s', mktime(23,59,59,$season*3,date('t',mktime(0, 0 , 0,$season*3,1,date("Y"))),date('Y'))),"\n";    echo "<pre>";      echo "<pre>";  $season = ceil((date('n'))/3)-1;//上季度是第几季度  echo '<br>上季度:<br>';  echo date('Y-m-d H:i:s', mktime(0, 0, 0,$season*3-3+1,1,date('Y'))),"\n";  echo date('Y-m-d H:i:s', mktime(23,59,59,$season*3,date('t',mktime(0, 0 , 0,$season*3,1,date("Y"))),date('Y'))),"\n";    echo "<pre>";     echo $season = ceil((date('n'))/3);//当月是第几季度  echo '<br>本季度:<br>';  echo date('Y-m-d H:i:s', mktime(0, 0, 0,$season*3-3+1,1,date('Y'))),"\n";  echo date('Y-m-d H:i:s', mktime(23,59,59,$season*3,date('t',mktime(0, 0 , 0,$season*3,1,date("Y"))),date('Y'))),"\n";      $season = ceil((date('n'))/3)+1;//当月是第几季度  echo '<br>下季度:<br>';  echo date('Y-m-d H:i:s', mktime(0, 0, 0,$season*3-3+1,1,date('Y'))),"\n";  echo date('Y-m-d H:i:s', mktime(23,59,59,$season*3,date('t',mktime(0, 0 , 0,$season*3,1,date("Y"))),date('Y'))),"\n";      echo "<pre>";     ?>