<?php

$p = "";//定義圓周率的兩種取值；

define("PI1",3.14);//定義變量PI變?yōu)槌Ａ?.14；

define("PI2",3.142);

$height = "中";//定義值得精度；

if($height == "中"){$p = "PI1";}

else if($height == "低"){$p = "PI2";}

$r = 1;

$area = constant($p)*$r*$r;

echo $area

?>

if($height == "中"){$p = "PI1";} ? ??

else if($height == "低"){$p = "PI2";}

????為什么分號(hào)要再中括號(hào)里面打。而不是外面，不是以分號(hào)結(jié)尾嗎