I'm trying to find a unique number from string which contain 4 numbers seprated by spaces in between them (not at start & end) & occurrence of these numbers should be 3.
I've tried like this but it gives me numbers with & without spaces which I don't want it should contain spaces in between them.

Example

(\d{4}.?){3}

above regex selects these as correct

1. 2131 2312 3675
2. 2131231212313675
3. 2131 1231 3675 - (this includes spaces at start & end)

In option (3) I can ignore spaces but I don't want output as option (2).

How can I fix this?

Live example

CodePudding user response：

Converting my comment to answer so that solution is easy to find for future visitors.

You may use this regex:

\b\d{4}(?: \d{4}){2}\b

RegEx Demo

RegEx Breakup:

• \b: Word boundary
• \d{4}: Match 4 digit
• (?: \d{4}){2}: Match a space followed by 4 digits. Repeat this group 2 times to make sure to match 3 sets separated by a single space.
• \b: Word boundary

CodePudding user response：

This should work: (?:\s*\b\d{4}\b){4}