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.
114
｜
第
5
章
使用花括号指明目标文件句柄的时候，默认是不会打印
$_
的内容的，你得自己明确
写出来：
print { $rocks_fh } $_;
根据实际编程需要，你可以自己决定选择使用裸字还是标量变量。对于一般短小的程
序，比如系统管理员的工具脚本，用裸字就够了。而对于稍大一点的项目或应用程
序，还是建议使用标量变量，从而精确控制文件句柄的作用范围，方便调试和维护。
习题
以下习题答案参见第
307
页上的“第
5
章习题解答”一节：
1. [7]
写一个功能跟
cat
相似的程序，但将各行内容倒序后输出（有些操作系统
会有一个名为
tac
的类似工具）。假如用
./tac fred barney betty
来运行
你的程序，它的输出结果应该是文件
betty
的最后一行到第一行，接着是文
件
barney
与
fred
，同样是由最后一行到第一行。（如果你将此程序取名为
tac
，
请一定要在运行时加上
./
，才不会运行你系统中现有的同名程序！）
2. [8]
写一个程序，要求用户分行键入各个字符串，然后以
20
个字符宽、向右对
齐的方式输出每个字符串。为了确定输出结果在适当的字段中，请一并输出由数
字组成的“标尺行（
rule line
）”（只是为了方便调试）。请确认自己没有误用
19
个字符的宽度！比如输入
hello
、
good-bye
后应该会得到下面这样的输出结
果：
123456789012345678901234567890123456789012345678901234567890 ...
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.