Question

I have a string that may contain a separator. This probably means that I have three cases:

First and only paragraph

---

First and only paragraph with redundant separator
<!-- separator -->

---

First paragraph
<!-- separator -->
Second paragraph

I need a regular expression that returns the first and second paragraph (if present) — separately. Here is what I have tried so far:

(.*)(<!-- separator -->.*)  // fails case 1
(.*)(<!-- separator -->.*)? // fails case 2 and 3 (surprise)

I just need the pattern.

Answer 1

The problem is probably, that the . does not match newline characters by default. You can change this by using the modifier s.

/(.*)(<!-- separator -->.*)?/s

s is the single line modifier, it makes the regex treat the input string as “singleline”, means the . will also match newline characters.

But you should then make the quantifier ungreedy, otherwise the first .* will match till the last <!-- separator --> in the string.

/(.*?)(<!-- separator -->.*)?/s