正则表达式查找第 n 个逗号并删除逗号和值

Question

正在尝试删除第 3 个逗号和逗号之后的值

a,b,c,d,e,f 
g,h,i,asj,k,l

如何编写正则表达式来找到 3 个逗号并删除 ,d 和 ,asj？我尝试了这个 /(?=(,[^,]{0,3}\n 但无法正常工作

Answer 1

您可以使用

^([^,]*(?:,[^,]*){2}),[^,]*

替换为 </code> 以恢复捕获的第 1 组值。见 <a href="https://regex101.com/r/oMC55A/1" rel="nofollow noreferrer">regex demo</a>. 详情: <ul> <li><code>^ - 字符串开头

([^,]*(?:,[^,]*){2}) - 第 1 组：

[^,]* - 逗号以外的零个或多个字符

(?:,[^,]*){2} - 出现两次逗号，然后是逗号以外的零个或多个字符

, - 逗号

[^,]* - 除逗号外的零个或多个字符。

Answer 2

在此处应用惰性匹配概念并在第 3 个逗号左右后删除值，请尝试按照显示的示例编写和测试的正则表达式。

^((?:.*?,){3})[^,]*,(.*)$

Online demo for above regex

说明：为上述正则表达式添加详细说明。

^((?:.*?,){3})  ##Matching from starting of value and creating 1st capturing group which has everything till 3rd comma in it. Using lazy match .*?
                ##to make sure its not a greedy match(in a non-capturing group, to avoid creating 2 groups).
[^,]*,          ##Matching everything till next occurrence of comma including that comma.
(.*)$           ##Creating 2nd capturing group which has everything in it till end of the value.

正则表达式查找第 n 个逗号并删除逗号和值

Regex to find the nth comma and remove the comma as well as the value

regex

regexp-replace