Re: sub string

[Kirk Waters <Kirk Waters noaa gov>]

Carlos,
rindex does the same thing as strrchr.  Couldn't tell you if either one
is POSIX off the top of my head.  They would have the advantage over
your approach because
a) You don't have to know how many directories deep you are.
b) As you pointed out, strtok is destructive to the original string,
which you may not want.

Kirk

Carlos Pereira wrote:
> 
> >> I have in the variable  gchar *aux = "name_of_directory/name_of_file";
> >> I want to copy only the substring /name_of_file to another gchar ...
> >> how can i do that??
> >> with strtok??
> 
> >You can do it with strtok or what I use is rindex:
> 
> >strcpy( new_string, rindex( aux, '/' ));
> 
> >is one way to do it.  This is pure C though, I don't know if there is a gtk*
> >way of doing it :)
> 
> rindex, what is that? I never heard of this and
> I can't find it on K&R or any of my C books...
> 
> You can do for example:
> 
> char *ptr;
> ptr = strtok (aux, "/"); /* ptr now points to name_of_directory */
> ptr = strtok (NULL, "/"); /* ptr now points to name_of_file */
> 
> 1) Everytime you call strtok, it returns a pointer to
> the next token contained between delimiters defined by
> the second parameter. You don't need to allocate
> memory for ptr, as it just points to somewhere in
> aux space.
> 
> 2) The NULL parameter in the second call tells strtok
> to keep using the aux string to search (internally this
> is done using a static variable). This way strtok continues
> searching from the place where it stopped last time.
> 
> 3) You can use as many delimiters as you want,
> for example ptr = strtok (aux, "\n\t \/*_#,.");
> or ptr = strtok (aux, string_containing_current_delimiters);
> 
> 4) you can change delimiters from one call to
> the next, even if the string remains the same.
> 
> 5) strtok automatically ends each token with
> a '\0', so you can handle the token using conventional
> techniques. However, this also means that strtok
> is a DESTRUCTIVE function. If you need the raw
> aux string later on, you should save it before
> it gets sliced by strtok (typically using strcpy).
> 
> 6) when strtok reaches the end of aux, it returns NULL, naturally.
> 
> 6) If you want to know more about advanced string
> handling on C, you might wish to grab a copy of
> 
> "Advanced C Programming by example", John W. Perry,
> PWS Publishing Company, Boston 1998.
> 
> Among other jewels it has a really good chapter
> on string handling (AINSI functions in depth, security, etc...).
> 
> Carlos
> 
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