<?php?
define("PI1",3.14);

$is1=defined("PI1");
$is2=defined("PI2");
if($is1==0){
????echo?"PI1?未被定義";
????}
else?{
????echo?"PI1?已被定義";
}
echo?"<br?/>";
echo?"<br?/>";
if($is2){
????echo?"PI2?已被定義";
????}
else?{
????echo?"PI2?未被定義";
}
echo?"<br?/>";
?>