[php] 常數constant搭配變數Variable使用

程式範例：

define("CAN_YOU_SPEAK_ENGLISH", "YES");
define("CAN_YOU_SPEAK_CHINESE", "YES");
define("CAN_YOU_SPEAK_JAPANESE", "NO");

$lang = "JAPANESE";
echo constant("CAN_YOU_SPEAK_".$lang);

輸出結果：
NO