php - Where did I go wrong in my regex lookaround? -

i'm trying pull first paragraph out of markdown formatted documents:

this first paragraph.

this second paragraph.

the answer here gives me solution matches first string ending in double line break.

perfect, except of texts begin markdown-style headers:

### h3 header.

this first paragraph.

so need to:

• skip line begins 1 or more # symbols.
• match first string ending in double line break.

in other words, return 'this first paragraph' in both of examples above.

so far, i've tried many variations on:

"/(?s)(?:(?!\#))((?!(\r?\n){2}).)*+/ 

but can't return proper match.

where did go wrong in lookaround?

i'm doing in php (preg_match()), if makes difference.

thanks!

you try

"/(?sm)^[^#](?:(?!(?:\r\n|\r|\n){2}).)*/" 

i enable multiline option using (?sm) instead of (?s) , start each check @ new line, may not starting #. , used \r\n|\r|\n instead of \r?\n because testing environment had funny line breaks =)