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Home Backend Development PHP Tutorial 正则:分组问题

正则:分组问题

Jun 06, 2016 pm 08:46 PM
php python regular expression

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<code><li><a href="/html/zjly/">走进临沂</a></li>

<li><a href="/html/csmp/">城市名片</a></li>

<li><a href="/html/tzys/">投资优势</a></li>

<li><a href="/html/zzcy/">支柱产业</a></li>

<li><a href="/html/xyjj/">县域经济</a></li>

<li><a href="/html/tzfw/">投资服务</a></li>

</code>

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正则1:

1

<code>(?</code>

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匹配结果
正则:分组问题


正则2:

1

<code>(?</code>

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匹配结果
正则:分组问题

问题
正则1和正则2只有中间的(\1)\"',按我的理解,此时的分组结果:\1要吗是"或',此时的正则表达式2((?)应该能够正常匹配url才对,而结果却不是这样的(如第2图所示)

回复内容:

数据

1

2

3

4

5

6

7

<code><li><a href="/html/zjly/">走进临沂</a></li>

<li><a href="/html/csmp/">城市名片</a></li>

<li><a href="/html/tzys/">投资优势</a></li>

<li><a href="/html/zzcy/">支柱产业</a></li>

<li><a href="/html/xyjj/">县域经济</a></li>

<li><a href="/html/tzfw/">投资服务</a></li>

</code>

Copy after login
Copy after login

正则1:

1

<code>(?</code>

Copy after login
Copy after login
Copy after login
Copy after login

匹配结果
正则:分组问题


正则2:

1

<code>(?</code>

Copy after login
Copy after login
Copy after login
Copy after login

匹配结果
正则:分组问题

问题
正则1和正则2只有中间的(\1)\"',按我的理解,此时的分组结果:\1要吗是"或',此时的正则表达式2((?)应该能够正常匹配url才对,而结果却不是这样的(如第2图所示)

([^(\1)]*)的问题在于方括号里面不能使用编号...

------------------

补充: \1在方括号是没有后向引用的作用的. \1在方括号中代表的意思是ctrl-a,16进制的\x01.就如\11匹配的是tab.
参考:Escape sequences

还有, \1如果有反向引用的作用,就有可能与 []是针对字符集里的单个字符为单位进行匹配这个规则冲突.所以,\1[]没有反向引用的作用.

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