查询今天是周几？

<?php 
$w=date('w'); 
$week=array( 
    "0"=>"星期日", 
    "1"=>"星期一", 
    "2"=>"星期二", 
    "3"=>"星期三", 
    "4"=>"星期四", 
    "5"=>"星期五", 
    "6"=>"星期六" 
); 
echo '今天是'.$week[$w];