Re: Strange behavior in search-forward-regexp?

[Barry Margolin <barmar@alum.mit.edu>]

In article <m2wtg21xhd.fsf@gmail.com>,
 Mathias Dahl <brakjoller@gmail.com> wrote:

> Take these "buffers":
> 
> Buffer 0:
> 
> ---------- this line is not part of the buffer ----------
> row0;test0
> row1;test1
> row2;test2
> ---------------------------------------------------------
> 
> Buffer 1:
> 
> ---------- this line is not part of the buffer ----------
> 
> row0;test0
> row1;test1
> row2;test2
> ---------------------------------------------------------
> 
> Evaluate these functions:
> 
> (defun test1 ()
>   (interactive)
>   (save-excursion
>     (goto-char (point-min))
>     (if (search-forward-regexp "^[^;]+;.*test1" nil t)
>         (message (match-string-no-properties 0)))))
> 
> (defun test2 ()
>   (interactive)
>   (save-excursion
>     (goto-char (point-min))
>     (if (search-forward-regexp "^.*test1" nil t)
>         (message (match-string-no-properties 0)))))
> 
> In buffer 0, test1 and test2 willreturn the same result, "row1;test1",
> but in buffer 1, test1 will return "\nrow1;test1" (\n is a newline)
> and test2 "row1;test1".
> 
> Can someone explain this to me? Why would, in the case of test1, the
> newline be included just because the line before is empty?

Because the regular expression . matches any character except newline, 
while [^;] matches any character except ';'.  So newline matches [^;].

-- 
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
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