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6.12 Define Endianness of a Variable: NF_DEF_VAR_ENDIAN

The function NF_DEF_VAR_ENDIAN sets the endianness for a variable in a netCDF-4 file.

This function must be called after the variable is defined, but before NF_ENDDEF is called.

By default, netCDF-4 variables are in native endianness. That is, they are big-endian on a big-endian machine, and little-endian on a little endian machine.

In some cases a user might wish to change from native endianness to either big or little-endianness. This function allows them to do that.

Usage

     NF_DEF_VAR_ENDIAN(INTEGER NCID, INTEGER VARID, INTEGER ENDIAN)

NCID

NetCDF ID, from a previous call to NF_OPEN or NF_CREATE.

VARID

Variable ID.

ENDIAN

Set to NF_ENDIAN_NATIVE for native endianness. (This is the default). Set to NF_ENDIAN_LITTLE for little endian, or NF_ENDIAN_BIG for big endian.

Errors

NF_DEF_VAR_ENDIAN returns the value NF_NOERR if no errors occurred. Otherwise, the returned status indicates an error.

Possible return codes include:

NF_NOERR

No error.

NF_BADID

Bad ncid.

NF_ENOTNC4

Not a netCDF-4 file.

NF_ENOTVAR

Can't find this variable.

NF_ELATEDEF

This variable has already been the subject of a NF_ENDDEF call. In netCDF-4 files NF_ENDDEF will be called automatically for any data read or write. Once enddef has been called, it is impossible to set the endianness of a variable.

NF_ENOTINDEFINE

Not in define mode. This is returned for netCDF classic or 64-bit offset files, or for netCDF-4 files, when they were been created with NF_STRICT_NC3 flag, and the file is not in define mode. (see NF_CREATE).

NF_EPERM

Attempt to create object in read-only file.

Example

In this example from nf_test/ftst_vars.c, a file is created with one variable, and its endianness is set to NF_ENDIAN_BIG.

     C     Create the netCDF file.
           retval = nf_create(FILE_NAME, NF_NETCDF4, ncid)
           if (retval .ne. nf_noerr) call handle_err(retval)
     
     C     Define the dimensions.
           retval = nf_def_dim(ncid, "x", NX, x_dimid)
           if (retval .ne. nf_noerr) call handle_err(retval)
           retval = nf_def_dim(ncid, "y", NY, y_dimid)
           if (retval .ne. nf_noerr) call handle_err(retval)
     
     C     Define the variable.
           dimids(1) = y_dimid
           dimids(2) = x_dimid
           retval = NF_DEF_VAR(ncid, "data", NF_INT, NDIMS, dimids, varid)
           if (retval .ne. nf_noerr) call handle_err(retval)
     
     C     Turn on chunking.
           chunks(1) = NY
           chunks(2) = NX
           retval = NF_DEF_VAR_chunking(ncid, varid, 0, chunks)
           if (retval .ne. nf_noerr) call handle_err(retval)
     
     C     Set variable to big-endian (default is whatever is native to
     C     writing machine).
           retval = NF_DEF_VAR_endian(ncid, varid, NF_ENDIAN_BIG)
           if (retval .ne. nf_noerr) call handle_err(retval)

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