1. Which of the following will not add john to the users array?

　　1. $users[] = ‘john’;

　　2. array_add($users,’john’);

　　3. array_push($users,’john’);

　　4. $users ||= ‘john’;

　　Answer: 2,4

　　2. What’s the difference between sort(), asort() and ksort(),rsort()? Under what circumstances would you use each of these?

　　sort(): 本函數(shù)對數(shù)組的值進(jìn)行排序。當(dāng)本函數(shù)結(jié)束時數(shù)組單元將被從最低到最高重新安排,array 中的單元賦予新的鍵名。這將刪除原有的鍵名而不僅是重新排序。

　　asort(): 這個函數(shù)將數(shù)組的值重新排序，由小至大排列。數(shù)組的索引亦跟著值的 順序而變動。當(dāng)您在程序中需要重新整理數(shù)組值的 順序時，就可以使用這個函數(shù)。

　　ksort(): 對數(shù)組按照鍵名排序，保留鍵名到數(shù)據(jù)的關(guān)聯(lián)。本函數(shù)主要用于關(guān)聯(lián)數(shù)組。

　　rsort(): 本函數(shù)對數(shù)組進(jìn)行逆向排序(最高到最低)。與sort()執(zhí)行相反的操作。

　　3. What would the following code print to the browser? Why?

　　$num = 10;

　　function multiply(){

　　$num = $num * 10;

　　}

　　multiply();

　　echo $num;

　　10

　　4. What is the difference between a reference and a regular variable? How do you pass by reference & why would you want to?

　　pass by reference like this functions(&$vars);

　　it likes more fast;

　　5. What functions can you use to add library code to the currently running script?

　　inlcude() or require();

　　6. What is the difference between foo() & @foo()?

　　if foo() throw a error, will be alert, but @foo() no;

　　7. How do you debug a PHP application?

　　xdebug or use die() do it;

　　8. What does === do? What’s an example of something that will give true for ‘==’, but not ‘===’?

　　=== 用于精確比較 ex: (” == null) => true but ( ”===null) =>false;