how to write regex for matching Reference # 11223344 for .net

sample data

Reference # 12345678

Regex I have tried this regex:

(?<=Reference #)[ ]\d{8}\b

I am getting space inside the match, how to remove it from the match and put in the look behind instead.

>Solution :

In PCRE (the option you used at the regex testing online Web site), you can use

Reference\s+#\s+\K\d{8}\b

See the regex demo.

In .NET, you can use

(?<=Reference\s+#\s+)\d{8}\b

See this regex demo.

Details:

• (?<=Reference\s+#\s+) – a positive lookbehind that matches a location that is immediately preceded with Reference + one or more whitespaces, # and then one or more whitespaces
• Reference – a word
• \s+#\s+ – a # char with one or more whitespaces both on the left and right
• \K – a match reset operator that discards the text matched so far from the overall match memory buffer
• \d{8} – eight digits
• \b – a word boundary (you might want to replace it with a right-hand digit boundary, (?!\d), if you plan to get a match if the eight digits are bordering on a letter or underscore).