I need a regular expression to extract a specific set of numbers from a string. The string could contain letters, special characters and spaces.

Input examples:

This is a test 99 12 3456
This is test 2 94123456
This is test 3 357 95123456
This is test 4 35797123 456
And so on…

The regex should look for a string of 8 numbers starting with 94 or 95 or 96 or 97 or 99 followed by 6 more numbers.

example:

94<6 more numbers here>
95<6 more numbers here>
96<6 more numbers here>
97<6 more numbers here>
99<6 more numbers here>

or 11 numbers starting with 357 followed by 94 or 95 or 96 or 97 and 6 more numbers.

example:

35794<6 more numbers here>
35795<6 more numbers here>
35796<6 more numbers here>
35797<6 more numbers here>
35799<6 more numbers here>

So the output should either be 8 numbers, or 11 numbers. Less than 8 or more than 11 is not a valid output. Also anything between 8 and 11 is not valid.

Hope this makes it more clear

Thanks for your help

CodePudding user response：

This regular expression will do it if you remove the spaces from the input first: 3579[4-9](?:\d{8}|\d{6})

CodePudding user response：

Maybe this:

(357|94|95|96)[\d ]{6,}

Which means "357" or "94" or "95" or "96" followed by at least six digits and/or spaces. I wasn't sure exactly what you want. It would be better just to post the exact input and output desired.

CodePudding user response：

If you’re working in an environment that supports lookbehinds, you can ensure you’re not matching a partial number by using a negative lookbehind and negative lookahead:

   /(?<!\d)(?:357)?9[4-79]\d{6}(?!\d)/

(?<!\d): Negative lookbehind (ensure there isn’t a digit before the matching expression)

(?:357)?: Create a non-capturing group of 357 to attach an optional quantifier (match 357 zero to 1 times)

9: Match 9

[4-79]: Character set with range 4-7 and 9 (match one of these characters)

\d{6}: Match a digit exactly 6 times

(?!\d): Negative lookahead (ensure there isn’t a digit after the matching expression)