My understanding is the argument "len" in nc_put_att_string()
is the number of strings, not strlen of one string.
Wei-keng
On Nov 1, 2017, at 1:29 PM, Dan Hitt wrote:
> Awesome!
>
> Thanks for cluing me in.
>
> I was indeed not setting the file type, which i'm now doing in nc_create() by
> nc_create( outfile, NC_NOCLOBBER | NC_NETCDF4, &ncid );
>
> So i no longer get kicked out with error -45.
>
> However, i am now segfaulting inside the nc_put_att_string() call,
> where it is apparently invoking strlen() (per gdb).
>
> So i wonder if there's another piece of setup that i am missing.
>
> Here's a complete program which illustrates the error (the malloc
> business at the top is to make sure that the string storage i pass in
> does not get optimized away or anything hokey like that):
>
> #include <stdlib.h>
> #include <stdio.h>
> #include <netcdf.h>
> #include <string.h>
>
> char* copy_string( const char* s ) {
> char* new_str = malloc( strlen(s) + 1);
> strcpy( new_str, s );
> return new;
> }
>
> int main(int argc,char** argv ) {
> char* outfile = "deleteme.nc";
> int ncid;
> int status = nc_create( outfile, NC_NOCLOBBER | NC_NETCDF4, &ncid );
> if ( status ) {
> fprintf(stderr,"Could not create `%s'; failed with status %d: %s\n",
> outfile, status, nc_strerror( status ) );
> return 1;
> }
> const char* key = copy_string( "my-key" );
> const char* val = copy_string( "my value" );
> status = nc_put_att_string( ncid, NC_GLOBAL, key, strlen(val), &val );
> if ( status ) {
> fprintf(stderr,
> "Failed on attempt to add string metadata; status %d: %s.\n",
> status, nc_strerror( status ) );
> return 2;
> }
> status = nc_close( ncid );
> if ( status ) {
> fprintf(stderr,"Failed on attempt to close %s; error %d: %s.\n",
> outfile, status, nc_strerror( status ) );
> return 3;
> }
> return 0;
> }
>
> If there's anything obvious wrong with this, please let me know, or if
> you have any suggestions for debugging, please let me know, and TIA!
>
> And thanks again for your earlier remark about the file type, which i
> would not have guessed.
>
> dan
>
>
>
> On Wed, Nov 1, 2017 at 8:59 AM, dmh@xxxxxxxx <dmh@xxxxxxxx> wrote:
>> Are you trying to create a netcdf-3 file, which does not
>> support string type.
>> =Dennis Heimbigner
>> Unidata
>>
>>
>> On 11/1/2017 1:15 AM, Dan Hitt wrote:
>>>
>>> Hi,
>>>
>>> I installed netcdf on a debian box using the the usual package means.
>>>
>>> I'm trying to assign some global string metadata in a file that i
>>> create, successfully, with nc_create().
>>>
>>> My statement to assign the metadata looks like this:
>>> int status =
>>> nc_put_att_string( ncid, NC_GLOBAL, key, strlen( value ), &value );
>>> where key and value both have declaration const char*.
>>>
>>> This compiles without error or warning, and i believe the values i'm
>>> passing in are innocuous.
>>>
>>> Nevertheless, at runtime, i get a return status of -45, which
>>> nc_strerror() reports as
>>> NetCDF: Not a valid data type or _FillValue type mismatch.
>>>
>>> Am i missing some piece of setup that i need to do (besides getting
>>> the ncid for the file)?
>>>
>>> This is my first call on the library after creating the file, so
>>> presumably my ncid for the file couldn't have gotten too messed up
>>> yet.
>>>
>>> TIA for any clues, or pointers to the manual, or any other advice.
>>>
>>> dan
>>>
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>>
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