August 2018
Beginner to intermediate
382 pages
7h 14m
Chinese
Content preview from Perl语言入门
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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.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.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.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.
148
｜
第
7
章
图
7
-
2
：用 \b 匹配单词边界
单词边界锚位非常有用，它保证我们不会意外地在
delicatessen
中找到
cat
，
在
boondoggle
中找到
dog
，或在
selfishness
中找到
fish
。有时候，你只会用到一个
单词边界锚位，像用
/\bhunt/
来匹配
hunt
、
hunting
或
hunter
，而排除了
shunt
；
或是用
/stone\b/
来匹配
standstone
或
flintstone
，但不包括
capstones
。
非单词边界锚位是
\B
，它能匹配所有
\b
不能匹配的位置。因此，模式
/\bsearch\B/
会
匹配
searches
、
searching
和
searched
，但不匹配
search
或
researching
。
Perl 5.22
和
5.24
又增加了一些更酷的单词锚位，不过你需要掌握更多匹配技巧才能
理解它们的工作原理。我们会在第
9
章谈及替换操作符时向你介绍。
习题
以下习题答案参见第
312
页上的
“第
7
章习题解答”一节。
如果正则表达式的运行超乎预料，不要惊讶，这很正常，初学者总是要花些时间，走
些弯路才能慢慢掌握它，所以本章练习尤为重要，请仔细完成：
1. [10]
编写程序，打印输入中带有
fred
的行（对其他行不用有任何操作）。测试
以下字符串是否可以匹配：
Fred
、
frederick
或
Alfred
。创建一个小型文本文
件，凑几行包含“
fred flintstone
”字样以及一些他朋友的名字的内容，然后用 ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
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.