Regex 正则表达式：为什么不‘；这不能捕捉到多次出现的双字母吗？

我想写一个正则表达式，让我能够找到包含三个或更多双字母（“oo”、“ss”、“tt”等）的文本文件中的所有行。下面是一个命令，我成功地使用它来查找包含两个或更多双字母的行：

egrep ‘(([A-Za-z])\2.*){2,}’ sherlock.txt

运行此命令生成的行的一个示例如下：

I had seen little of Holmes lately. My marriage had drifted us away from each

这一行实际上包含三个双字母（“ee”、“tt”和“rr”）。但是，当我使用以下命令打印包含三个或更多双字母的行时，没有输出：

egrep ‘(([A-Za-z])\2.*){3,}’ sherlock.txt

---

为什么这个代码不起作用？我遗漏了什么？

由于您没有提供您正在使用的语言/工具，下面是一个perl oneliner，它可以完成这项工作：

输入文件：

cat file.txt 
I had seen little of Holmes lately. My marriage had drifted us away from each
I had seen Holmes lately. My marriage had drifted us away from each

perl -anE '@l=$_=~/(\w)\1/g;say if @l>2' file.txt 

I had seen little of Holmes lately. My marriage had drifted us away from each

Perl:

cat file.txt 
I had seen little of Holmes lately. My marriage had drifted us away from each
I had seen Holmes lately. My marriage had drifted us away from each

perl -anE '@l=$_=~/(\w)\1/g;say if @l>2' file.txt 

I had seen little of Holmes lately. My marriage had drifted us away from each

输出：

cat file.txt 
I had seen little of Holmes lately. My marriage had drifted us away from each
I had seen Holmes lately. My marriage had drifted us away from each

perl -anE '@l=$_=~/(\w)\1/g;say if @l>2' file.txt 

I had seen little of Holmes lately. My marriage had drifted us away from each

---

（[A-Za-z]）\2.*{3，}

试试这个：（[A-Za-z]）\2.*++问题来自于您使用贪婪匹配的事实，最好先将

*

放在

（\w）\2）{3}

的前面，但任何一种方法都应该有效，即使

（.[\w）\2）{3}.*

如果需要整个字符串的话