PHP面试题附答案

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(): 本函数对数组的值进行排序。当本函数结束时数组单元将被从最低到最高重新安排,array 中的单元赋予新的键名。这将删除原有的键名而不仅是重新排序。
asort(): 这个函数将数组的值重新排序，由小至大排列。数组的索引亦跟着值的 顺序而变动。当您在程序中需要重新整理数组值的 顺序时，就可以使用这个函数。
ksort(): 对数组按照键名排序，保留键名到数据的关联。本函数主要用于关联数组。
rsort(): 本函数对数组进行逆向排序（最高到最低）。与sort()执行相反的操作。
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 ‘===’?
=== 用于精确比较 ex: (” == null) => true but ( ”===null) =>false;
9. How would you declare a class named “myclass” with no methods or properties?
class myclass{
}
10. How would you create an object, which is an instance of “myclass”?
$myoject = new myclass();
11. How do you access and set properties of a class from within the class?
getVar() or setVar() ;
12. What is the difference between include & include_once? include & require?
require:PHP 程式在执行前，就会先读入 require 所指定引入的档案，使它变成 PHP 程式网页的一部份。常用的函式，亦可以这个方法将它引入网页中。错误产生致命错误。
include:这个函式一般是放在流程控制的处理区段中。PHP 程式网页在读到 include 的档案时，才将它读进来。这种方式，可以把程式执行时的流程简单化。错误产生警报。
include_once:此行为和include()语句类似，唯一区别是如果该文件中的代码已经被包含了，则不会再次包含。如同此语句名字暗示的那样，只会包含一次。
13. What function would you use to redirect the browser to a new page?
1. redir()
2. header()
3. location()
4. redirect()
2
14. What function can you use to open a file for reading and writing?
1. fget();
2. file_open();
3. fopen();
4. open_file();
3
15. What’s the difference between mysql_fetch_row() and mysql_fetch_array()?
mysql_fetch_row():返回根据所取得的行生成的数组，如果没有更多行则返回 FALSE。
mysql_fetch_array(): 是mysq_fetch_row()的扩展版本。除了将数据以数字索引方式储存在数组中之外，还可以将数据作为关联索引储存，用字段名作为键名。
16. What does the following code do? Explain what’s going on there.
$date=’08/26/2003′;
print ereg_replace(‘([0-9]+)/([0-9]+)/([0-9]+)’,’2/1/3′,$date);
本函数以 正则 的规则来解析比对字符串 ，欲取而代之的字符串为’2/1/3′。
返回值为字符串类型，为取代后的字符串结果。
17. Given a line of text $string, how would you write a regular expression to strip all the HTML tags from it?
strip_tags
18. What’s the difference between the way PHP and Perl distinguish between arrays and hashes?
19. How can you get round the stateless nature of HTTP using PHP?
20. What does the GD library do?
21. Name a few ways to output (print) a block of HTML code in PHP?
22. Is PHP better than Perl? – Discuss.
如果成功则返回 TRUE，失败则返回 FALSE。