sscanf sequential assignment?

[Stephen Clamage]

berg at marvin.e17.physik.tu-muenchen.de (Stephen R. van den Berg) writes:

>Does the Standard say anything about a guaranteed assignment sequence
>for sscanf?

>i.e.:  char *str,*p,dest[80];

>       sscanf(str," %n%s %n",&p,dest,&p);

>Will p guaranteed to get it's value from the second '%n' if 'str'
>doesn't point to an empty or all whitespace string?

Your code is incorrect, so lets fix it first.  The argument corresponding
to the %n must be of type int*, but yours is type char**.  Try this:
	char *str, dest[80];
	int p;
	sscanf(str, " %n%s %n", &p, dest, &p);
The Standard requires that scanf execute each directive in turn, so
if str is ok, p must get the value of the second %n.

>Since we're at it anyway, what about backward portability with older
>libraries, do all old libs support the '%n' identifier too?

No, not all older libraries support %n.  Some libraries support %n but
not %hn, where the corresponding argument points to a short.
-- 

Steve Clamage, TauMetric Corp, steve at taumet.com