January 2021
Intermediate to advanced
505 pages
9h 45m
Chinese
Content preview from PHP编程：第4版
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词法结构
｜
21
$not valid
$|
$3wa
由于区分大小写，下面这些变量是完全不同的 ：
$hot_stuff $Hot_stuff $hot_Stuff $HOT_STUFF
函数名
函数名不区分大小写（第
3
章会详细讨论函数）。以下是一些合法的函数名 ：
tally
list_all_users
deleteTclFiles
LOWERCASE_IS_FOR_WIMPS
_hide
下面这些函数名都指向相同的函数 ：
howdy HoWdY HOWDY HOWdy howdy
类名
类名遵循
PHP
标识符的标准规则并且不区分大小写，以下是一些合法的类名 ：
Person
account
类名
stdClass
被保留。
常量
常量是一个值不会改变的标识符，只有标量值（布尔型、整数、双精度浮点数和字符串）
和数组可以是常量。一旦设置，常量的值就不能改变。可以通过标识符引用字面量或通
过
dene()
函数设置常量 ：
define('PUBLISHER', "O'Reilly Media");
echo PUBLISHER;
关键字
关键字（或保留字）是
PHP
为了其核心功能而预留的单词，在对变量、函数、类或常量
命名时，不能使用和关键字相同的名字。表
2-1
列出了
PHP
中的关键字。关键字是不区
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.