PHP ʖ²ἯTH º󍋼/A Ղ 9. ³£ Ŀ¼ ӯ·¨ Ԥ¶¨ҥ³£ ӯ·¨ ³£ºͱ䁿²»ͬ£º ³£һµ©¶¨ҥ¾Ͳ»Ĝ±»֘Ђ¶¨ҥ»򕟈¡ϻ¶¨ҥ£» ³£µĖµֻĜʇ±ꁿ¡£ =ד 9-1. ¶¨ҥ³£ ?php define("CONSTANT", "Hello world."); echo CONSTANT; // outputs "Hello world." echo Constant; // outputs "Constant" and issues a notice.? º󍋼/A ưµ㼯A PHP µčⲿ±䁿 ɏһ¼¶ Ԥ¶¨ҥ³£