but there is a possibility that yours won't cater for: A string containing < 40 chars but no newline..

You're right. Mine doesn't account for it. I guess I assumed they all would end with newlines. That was a bad assumption on my part. Of course, I might blame it on poorly stated requirements. :-)

(Knowing you, you'll add a 4 character, positively backward, forward-looking, zero-width assertion to your regex and acheive that too:)

Nah... it should be easier than that. Use a $ to match the end of the line (not including the newline) and then \n? to match an optional newline. So, I tried that:

/
(                 # Assuming you want capture these lines.
  (?:             # Group each line.
     ^            # Beginning of the line.
     .{0,40}$\n?  # 0 to 40 chars, an end-of line and optional newline
+. 
  ){1,4}          # 1 to 4 lines. (0 will permit an empty match.)
)                 # Done capturing.
/mx;              # /m so that ^ anchor works, /x for comments.
[download]

But that didn't work! I was vexed until I realized that looks an awful lot like "match 0 to 40 characters followed by $\ followed by an optional "n". So, then I tried:

/
(               # Assuming you want capture these lines.
  (?:           # Group each line.
     ^          # Beginning of the line.
     .{0,40}$   # 0 to 40 characters followed by an end-of-line.
     \n?        # An optional newline. 
  ){1,4}        # 1 to 4 lines. (0 will permit an empty match.)
)               # Done capturing.
/mx;            # /m so that ^ anchor works, /x for comments.
[download]

And that worked like a charm.

That additional requirement did make the whole exercise more fun. There is another workaround. Sometime before I actually figured out why it was breaking, I tried (?:\n|\Z) and that worked as well but I thought it was ugly. So, I'm left wondering whether there is a better way around it than using /x and whitespace.

Thanks for making this so much more entertaining. :-)

Update: This was my 300th node! :-)

-sauoq
"My two cents aren't worth a dime.";