On 11-06-09 7:27 AM, oliver wrote:
On Wed, Jun 08, 2011 at 08:35:34PM -0400, Simon Urbanek wrote:
On Jun 8, 2011, at 8:32 PM, oliver wrote:
On Thu, Jun 09, 2011 at 02:17:31AM +0200, oliver wrote:
[...]
OK, I looked at this now.
LENGTH() checks the length of the vector.
Good to know this.
So the problem of a vector of length 0 can be with any arguments of type SEXP,
hence I will need to check ANY arg on it's length.
This is vital to stability under any situation.
Thanks for this valuable hint!
I will add checks for all my SEXP-args.
[...]
Hey, LENGTH() does not work with String-vectors! :(
Of course it does ...
It does not so on my R 2.10.1 installation.
In the R-Shell I get:
==============================
> length(c())
[1] 0
>
==============================
So c() is vec of length 0.
When I feed my readjpeg() with c() as filename arg,
testing with:
====================================================
if( LENGTH( filename_sexp )< 1 )
{
error("LENGTH( filename_sexp )< 1");
//error("filename can't be vector of length 0");
}
else
{
error("LENGTH( filename_sexp ) is not< 1");
}
====================================================
I got:
Error in readjpeg(filename = c()) : LENGTH( filename_sexp ) is not< 1
You can explain why?
c() doesn't create a STRSXP, it is NULL, which is a NILSXP. LENGTH()
doesn't work on that object. (I'd recommend using length() rather than
LENGTH(); it's a function, not a macro, and it does give the expected
answer.)
Duncan Murdoch
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
