Accessing Attributes with put_attr() and get_attr()

int (*get_att)(int ncid, int varid, const char *name,
                    void *value, nc_type memtype);

int (*put_att)(int ncid, int varid, const char *name, nc_type datatype, size_t len,
               const void *value, nc_type memtype);

Again, the key difference is the memtype parameter. As with put/get_vara, it used NC_INT64 to encode the long case.