Regex for the last line of a string

Question

I'm trying to search for the last line in a string (lines separated by \n) using string match but I cannot make it work as intended. The code below evaluates to 0 while I would have expected 4. I guess my regex is wrong (it was supposed to be a newline (\n) followed by anything but a newline (.*) until the end of the string ($).

(string-match "\n.*$" "\n \n \n ")

Answer 1

$ matches at the end of a line, not the end of a string. If you want to match at the end of a string you need to use the \' operator:

(string-match "\n.*\\'" "\n \n \n ")
=> 4

See (info "(elisp)Regexp Backslash") for more details (or Regexp-Backslash)