August 2018
Beginner to intermediate
382 pages
7h 14m
Chinese
Content preview from Perl语言入门
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Perl
模块
｜
209
#
也是在你的
Perl
程序内部
use lib qw( /Users/fred/perl5 );
作为起步，上面这些应该够了。我们在《
Intermediate Perl
》中会有更深入的讨论，包
括教你编写自己的模块。其他相关信息不妨参阅
perlfaq8
文档。
使用简易模块
假设在程序里有个包含路径的长文件名，比如
/usr/local/bin/perl
，而你希望取出文件
的基名（
basename
）而不包括目录。这其实很简单，文件的基名就是最后一个斜线之
后的内容（此例中即为
perl
）：
my $name = "/usr/local/bin/perl";
(my $basename = $name) =~ s#.*/##;
和你之前看到的一样，
Perl
会先在圆括号中进行赋值，然后再进行替换操作：将结尾
为斜线的字符串（也就是文件路径的目录部分）替换成空字符串，这样就只剩下基名
了。或者采用更为简洁的写法，在替换操作中使用
/r
开关：
use v5.14;
my $name = "/usr/local/bin/perl";
my $basename = $name =~ s#.*/##r;
如果这么写，看起来好像可以正常工作。好吧，这只是看起来，实际上这么写隐含着
三个问题。
首先，
Unix
上的文件或目录名称可能会包含换行符（这虽然不是常常发生，但
确实可能发生）。由于正则表达式的点号（
.
）无法匹配换行符，像
"/home/fred/
flintstone\n/brontosaurus" ...
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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.
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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.