Comment author: administrator

Hello,

%N returns one more character than I would expect. For example:

sscanf "456" "%N" (fun x -> x)

returns 1, and not 0 ("the number of characters read so far", as stated in the docs).

And

sscanf "" "%N" (fun x -> x)

raises the exception End_of_file.

This is indeed a bug that no one here have noticed, even after careful
code review! (Not mentioning intensive testing on complex formats!)

Thank you very much for pointing it out.

I found this error because I needed a way to check that the whole buffer is
read, and
not just a prefix. So I thought that

sscanf iso_date_string 
       "%4d-%2d-%2d%N" 
       (fun year month day n -> 
         if n = String.length iso_date_string then
           (year,month,day)
         else
           Scanf.Scan_failure "Too many characters")

solved my problem, but it did not. Maybe it is a usuful extension to add a
notation like $ in regexps that anchors at the end of strings.

I am not completely sure that we need the $ extension.

The correction of those glitches is not completely trivial and I am
working on them. I will drop you a mail as soon as I have a
satisfactory correction.

Thank you again for reporting the bug.

Pierre Weis

INRIA, Projet Cristal, Pierre.Weis@inria.fr, http://pauillac.inria.fr/~weis/

Comment author: administrator

fixed by PW at some unspecified date