Re: Question about possible error in netCDF manual

> Organization: NOAA/CDC
> Keywords: 199404201748.AA15020

Hi Don,

>       My name is Don Hooper.  I work for NOAA's Climate Diagnostics
> Center.  I've been working on some netCDF applications, and I'm
> thinking I may have come across an error in the documentation for
> the ncattinq function.  The manual for version 2.3 states that,
> for character type attributes, the length returned is one plus the
> length of the string, as the null is stored.
> 
> I use a couple of attributes whose values take the form
> "yyyy-mm-dd hh:mm:ss".  I count the length of that string as 19, and
> when I create my netCDF files, I set the length of the attribute to
> 20 when I call ncattput, as the manual states to count the null.  Yet,
> when in another program that reads this netCDF file I call ncattinq on
> this attribute, it returns 19 for the length.
> 
> I don't see a problem with the netCDF library either counting the
> null or not counting it, as long as it's consistent between
> ncattput and ncattinq, and the documentation accurately reflects
> the actual convention.
> 
> It is, of course, possible that I'm in error about my facts.  I just
> thought I'd ask if this was a known problem with the documentation.
> Thanks very much for your time.

I can't duplicate the problem here.  I just compiled and ran the following
program linked against the netcdf library:

-------------------------------------------------- cut here -----------------
#include <stdio.h>
#include "netcdf.h"

main() {
    int ncid, len;

    ncid = nccreate("atlen.nc", NC_CLOBBER);
    ncattput(ncid, NC_GLOBAL, "title", NC_CHAR, 10, "The title");
    /* Get the length of the attribute that was just stored */
    ncattinq(ncid, NC_GLOBAL, "title", (nc_type *)0, &len);
    ncclose(ncid);

    printf("Should be 10: %d\n", len);
}
-------------------------------------------------- cut here -----------------

and the result of running the program was:

        Should be 10: 10

as expected.  If you could supply a small example program that demonstrates
the problem you described, I could see if we can duplicate it and determine
whether there is a bug.  The documentation says the extra NULL should be
counted both for the ncattput() and ncattinq() calls, so If the library
isn't behaving this way, it is definitely a bug.

__________________________________________________________________________
                      
Russ Rew                                              UCAR Unidata Program
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