RegEx VB.NET part of string

Question

I have a regex witch searches for dates (0[1-9]|[12][0-9]|3[01])[- /.](0[1-9]|1[012])[- /.](20)\d\d.

The problem is that it also returns matches where the match is within another string like 10.10.10.2019 it matches 10.10.2019 as a date. Tried with \b at the beginning and end but no luck. Also used ^ and $ but still no luck.

Wiktor Stribiżew · Accepted Answer · 2016-12-15 20:36:19Z

1

You need to use lookarounds to only match in between whitespaces or start/end of string:

(?<!\S)(?:0?[1-9]|[12][0-9]|3[01])([- /.])(?:0?[1-9]|1[012])\k<1>20\d\d(?!\S)
^^^^^^^                                                                ^^^^^^

See the regex demo

I also suggest to check for the identical separators by capturing the first separator with ([- /.]) and then using \k<1> (unambiguous) backreference to match the same value.

edited Dec 15, 2016 at 20:36

answered Dec 14, 2016 at 12:14

Wiktor Stribiżew

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Wotikar Over a year ago

The regex you supplied doesn't recognize this date format 1-1-2016

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