Regex 神秘的perl表达式
我在perl（实际上是PDL）程序中发现以下语句： 有人能帮我这个perl编程的学徒解码吗Regex 神秘的perl表达式,regex,perl,pdl,Regex,Perl,Pdl,我在perl（实际上是PDL）程序中发现以下语句： 有人能帮我这个perl编程的学徒解码吗 /\/([\w]+)$/i; 它是一个正则表达式，如果它是一个完整的语句，它将应用于$\uu变量，如下所示： $_ =~ /\/([\w]+)$/i; 它查找斜杠\/，后跟字母数字字符串\w+，后跟行尾$。它还捕获字母数字字符串（），该字符串在变量$1中结束。结尾的/i使其不区分大小写，在本例中无效。这是将$\u与后跟一个或多个字符的斜杠（不区分大小写）进行比较，并将其存储在$1 $_ value
/\/([\w]+)$/i;
$\uu$_ =~ /\/([\w]+)$/i;
它查找斜杠
\/\w+$（）$1/i$\u$1$_ value then $1 value
------------------------------
"/abcdes" | "abcdes"
"foo/bar2" | "bar2"
"foobar" | undef # no slash so doesn't match
当然，我会从里到外解释：
\w[…][\w]+[\w]+（…）（[\w]+）$（[\w]+）$\/\/（[\w]+）$/…//…/i/\/（[\w]+）$/i-匹配一行中的最后一个单词，并记住它以备将来使用；这个词必须在斜杠后面。基本上，从绝对路径获取文件名。不区分大小写的部分不相关，\w
将已经匹配这两种情况
有关Perl正则表达式的更多详细信息，请参见：
正如JRGUSON所指出的，它对于标记正则表达式和解释各个部分非常有用。您会发现该模块值得安装
#!/usr/bin/env perl
use YAPE::Regex::Explain;
#...may need to single quote $ARGV[0] for the shell...
print YAPE::Regex::Explain->new( $ARGV[0] )->explain;
假设此脚本名为“Rexplane”，请执行以下操作：
$ ./rexplain '/\/([\w]+)$/i'
…获得：
The regular expression:
(?-imsx:/\/([\w]+)$/i)
matches as follows:
NODE EXPLANATION
----------------------------------------------------------------------
(?-imsx: group, but do not capture (case-sensitive)
(with ^ and $ matching normally) (with . not
matching \n) (matching whitespace and #
normally):
----------------------------------------------------------------------
/ '/'
----------------------------------------------------------------------
\/ '/'
----------------------------------------------------------------------
( group and capture to \1:
----------------------------------------------------------------------
[\w]+ any character of: word characters (a-z,
A-Z, 0-9, _) (1 or more times (matching
the most amount possible))
----------------------------------------------------------------------
(with ^ and $ matching normally) (with . not
matching \n) (matching whitespace and #
normally):
----------------------------------------------------------------------
/ '/'
----------------------------------------------------------------------
\/ '/'
----------------------------------------------------------------------
( group and capture to \1:
----------------------------------------------------------------------
[\w]+ any character of: word characters (a-z,
A-Z, 0-9, _) (1 or more times (matching
the most amount possible))
----------------------------------------------------------------------
) end of \1
----------------------------------------------------------------------
$ before an optional \n, and the end of the
string
----------------------------------------------------------------------
/i '/i'
----------------------------------------------------------------------
) end of grouping
----------------------------------------------------------------------
更新：
另见：。如模块文档中所述：
不支持Perl 5.6版之后添加的正则表达式语法，尤其是任何
5.10中添加的构造
这个问题值得一提。下面是一个例子来解释正则表达式的含义，并粘贴在这里以供记录
顺序：按顺序匹配以下所有内容
虽然它不能帮助“解释”正则表达式，但一旦你有了一个测试用例，Damian的新工具是一个很酷的工具，可以观察匹配过程中实际发生了什么。安装它，然后在命令行执行rxrx
以启动调试器，然后键入/\/（[\w]+）$/
和'/r'
（例如），最后键入m
以启动匹配。然后可以通过反复按enter键逐步完成调试器。真的很酷 谢谢Tim…非常好的描述，完全符合代码的上下文。看来我需要更多的正则表达式经验后，40多年的编程<代码>$1The regular expression:
(?-imsx:/\/([\w]+)$/i)
matches as follows:
NODE EXPLANATION
----------------------------------------------------------------------
(?-imsx: group, but do not capture (case-sensitive)
(with ^ and $ matching normally) (with . not
matching \n) (matching whitespace and #
normally):
----------------------------------------------------------------------
/ '/'
----------------------------------------------------------------------
\/ '/'
----------------------------------------------------------------------
( group and capture to \1:
----------------------------------------------------------------------
[\w]+ any character of: word characters (a-z,
A-Z, 0-9, _) (1 or more times (matching
the most amount possible))
----------------------------------------------------------------------
(with ^ and $ matching normally) (with . not
matching \n) (matching whitespace and #
normally):
----------------------------------------------------------------------
/ '/'
----------------------------------------------------------------------
\/ '/'
----------------------------------------------------------------------
( group and capture to \1:
----------------------------------------------------------------------
[\w]+ any character of: word characters (a-z,
A-Z, 0-9, _) (1 or more times (matching
the most amount possible))
----------------------------------------------------------------------
) end of \1
----------------------------------------------------------------------
$ before an optional \n, and the end of the
string
----------------------------------------------------------------------
/i '/i'
----------------------------------------------------------------------
) end of grouping
----------------------------------------------------------------------
/ (slash)
--+
Repeat | (in GroupNumber:1)
AnyCharIn[ WordCharacter] one or more times |
--+
EndOfLine