正则表达式匹配包含至少3个破折号/连字符的字符串

Question

I have an email body. It contains several lines of text. I need to extract the first occurrence of a string that:

1. comes after a specific text
2. contains at least 3 dashes

The shape of the dashed string is unknown. It may contain letters and numbers of any number, ie: AA3A-123-NNN-D or 12-OOO-12455-AS

For example:

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Donec imperdiet porta libero ac imperdiet.

Nam enim nisl: aliquam ut feugiat vitae

Specific text after which I need to search: Etiam rhoncus AAFA-12X-DDDD-12 metus risus More text: foo

Target language is C#.

I've tried doing something like ([A-Za-z0-9]{5}-[A-Za-z0-9]{4}-[A-Za-z0-9]{3}-[A-Za-z0-9]{5}) but as you can see here I need to set the shape of the string which is not always known.

Answer 1

You can use a lazy quantifier with [\\s\\S] :

(?:Specific\ text\ after\ which\ I\ need\ to\ search:)
[\s\S]+?\K
(\b\w+-\w+-\w+-\w+\b)

The \\b is a word boundary, \\K deletes everything to the left from the match.
See a demo on regex101.com .

Answer 2

If your expression contains an unknown number of letters and numbers the best you can do is specify a range for your regular expression. I see in your examples the most a block has is 5 characters and least one has is 1 character.

So something like this will capture it,

([A-Za-z0-9]{1,5}-[A-Za-z0-9]{1,5}-[A-Za-z0-9]{1,5}-[A-Za-z0-9]{1,5})

Answer 3

I'd go with something like (?:[a-zA-Z0-9]+-){3,}[a-zA-Z0-9]+ . What this will do is match 3 or more groups of alphanumerics ending with a dash, followed by one that doesn't.

Try it yourself on Regex101 .