Hello,

Francois Colonna wrote:
> Hello
> 
> in the version of the O'Reilly book on the web
> http://caml.inria.fr/pub/docs/oreilly-book/html/book-ora105.html#toc134
> 
> Chapter 11 about Str Library page 293
> 
> the followin example of a regular expression is given :
> 
> *let*| |english_date_format| ||=|| |Str.regexp| 
> ||"[0-9]+\.[0-9]+\.[0-9]+"|| |;;

There should be a double backslash \\.
Indeed \ is a meta-chararcter of regular expressions, but also
of usual strings.
In general, all backslashes in regular expressions must be
doubled when represented as caml strings. For instance, the
same happens with groupings :

the regular expression : \([0-9]+\),\1

is represented by

let re = Str.regexp "\\([0-9]+\\),\\1"

Hope it helps,
Sebastien