20040608: _LARGE_FILES in netCDF

Charlie,

> To: netCDF Support <address@hidden>
> cc: Charlie Zender <address@hidden>
> From: zender <address@hidden>
> Subject: _LARGE_FILES in netCDF
> Organization: UCI
> Keywords: 200406081710.i58HATtK011254Q netCDF large file

The above message contained the following:

> I'm trying to figure out when to use/not use
> 
> -D_LARGE_FILES 
> 
> when building netCDF. 
> I can find any documentation on exactly what it does. 
> I've tried glimpse on the mail lists etc, unsuccessfully.
> I only see it in the AIX installation examples.
> Please clarify its usage.

The AIX operating system supports access to large files if the C macro
"_LARGE_FILES" is defined when the code that accesses such files is
compiled.  Large files require that the "off_t" datatype be a 64-bit
integer.  In practice, this means that if you intend to create or read
netCDF files on an AIX system that are larger than 2 gigabytes, then
you should compile the netCDF library with the C macro "_LARGE_FILES"
defined.  A library compiled this way can always access netCDF files
created on other systems (or the same system) regardless of whether or
not the other netCDF library was compiled with large file support.

Examples of this can be found at

    http://my.unidata.ucar.edu/content/software/netcdf/INSTALL.html#aix

Other operating systems require that a different C macro be defined in
order to access large files or they don't support access to large files
at all (regardless of any C macro).

> Thanks,
> Charlie
> -- 
> Charlie Zender, address@hidden, (949) 824-2987, Department of Earth 
> System Science, University of California, Irvine CA 92697-3100 

Regards,
Steve Emmerson

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