PHP ʖ²ἯTH º󍋼/A Ղ 13. º¯ʽ Ӄ»§ה¶¨ҥº¯ʽ function foo ($arg_1, $arg_2,..., $arg_n) {echo "Example function.\n"; return $retval;} =ד 13-1. Ӑ̵¼þµĺ¯ʽ ?php $makefoo = true; /* We can't call foo() from here since it doesn't exist yet, but we can call bar() */ bar(); if ($makefoo) {function foo () {echo "I don't exist until program execution reaches me.\n";}} /* Now we can safely call foo() since $makefoo evaluated to true */ if ($makefoo) foo(); function bar() {{echo "I exist immediately upon program start.\n";}? =ד 13-2. º¯ʽ֐µĺ¯ʽ ?php function foo() {function bar() {echo "I don't exist until foo() is called.\n";}} /* We can't call bar() yet since it doesn't exist. */ foo(); /* Now we can call bar(), foo()'s processesing has made it accessable. */ bar();? PHP ²»֧³ֺ¯ʽ֘Ԙ£¬¿Ʉܒ²²»֧³ֈ¡ϻ¶¨ҥ»򕟖ض¨ҥґɹ÷µĺ¯ʽ¡£ º󍋼/A ưµ㼯A include_once() ɏһ¼¶