php获取今天是星期几

$da = date("w");
if( $da == "1" ){
echo "今天是星期一";
}else if( $da == "2" ){
echo "今天是星期二";
}else if( $da == "3" ){
echo "今天是星期三";
}else if( $da == "4" ){
echo "今天是星期四";
}else if( $da == "5" ){
echo "今天是星期五";
}else if( $da == "6" ){
echo "今天是星期六";
}else if( $da == "0" ){
echo "今天是星期日";
}else{
echo "你输入有误!!";
};

$ga = date("w");
switch( $ga ){
case 1 : echo "今天是星期一";break;
case 2 : echo "今天是星期二";break;
case 3 : echo "今天是星期三";break;
case 4 : echo "今天是星期四";break;
case 5 : echo "今天是星期五";break;
case 6 : echo "今天是星期六";break;
case 0 : echo "今天是星期日";break;
default : echo "你输入有误！";
};

mb_substr ( string $str , int $start [, int $length = NULL [, string $encoding = mb_internal_encoding() ]] ) : string

echo "今天是星期" . mb_substr( "日一二三四五六",date("w"),1,"utf-8" );