How to match a fixed number of digits with regex in PHP?

Question

I want to retrieve the consecutive 8 digits out of a string.

"hello world,12345678anything else"

should return 12345678 as result(the space in between is optional).

But this should not return anything:

"hello world,123456789anything else"

Because it has 9 digits,I only need 8 digits unit.

Answer 1

Try

'/(?<!\d)\d{8}(?!\d)/'