大牛们好,php新手问几个面试题
- PHP code
<!-- Code highlighting produced by Actipro CodeHighlighter (freeware) http://www.CodeHighlighter.com/ --> 1. $a = 3; $b = 2; echo (int)$a/(int)$b 为什么输出是 1.5? 2. How can you hide the fact that web pages are written in PHP? a. By using AddType application/X-httpd-php asp b. Specify all file names without any dot and extension c. By using .htaccess diretive in Apeche d. All of the above 3. 解释一下Using Register Globals。
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1. 因为1)/是除法操作符,不是整除操作符 2)(int)操作符优先级高于/
所以 (int)$a/(int)$b = 3 / 2 = 1.5
2. 我选择d
3. Using Register Globals的场合,提交的变量可以直接通过 $变量名 使用。
但是存在安全问题,建议不要用Register Globals.
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(int)作用于变量,而非整个表达式
(int)($a/$b);如此结果是1
2 事实上这些措施还不够,最好能重编译apache,改写web服务器输出头,隐藏开发语言是php的信息
3 是已经非常不推荐的功能了
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楼上二位
在 C 里 (int)a/(int)b 可是等于 1 的噢
这道题就源于这里
考点是数据类型的自动变换,两个整型数相除结果为什么是浮点数
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好像说到没啥意义的地方去了。或者说根本没必要这么去做
数据类型
根源还是在于php转换数据类型太容易了,hoho
强类型的语言,一般都会以a、b当中,精度更高的作为结果返回

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