f_format_variants.f90 File Reference

Demonstrates all five NetCDF binary format variants in Fortran. More...

Functions/Subroutines
program	f_format_variants
subroutine	populate_file (ncid)

Detailed Description

Demonstrates all five NetCDF binary format variants in Fortran.

This is the Fortran equivalent of format_variants.c, demonstrating all five NetCDF binary format variants using the Fortran 90 NetCDF API. The program creates identical data structures in each format and compares their characteristics.

Learning Objectives:

• Understand format flags in Fortran (NF90_CLASSIC_MODEL, NF90_64BIT_OFFSET, NF90_64BIT_DATA, NF90_NETCDF4, IOR(NF90_NETCDF4, NF90_CLASSIC_MODEL))
• Learn format detection with nf90_inq_format()
• Compare file sizes and format characteristics
• Make informed format choices in Fortran applications

Fortran Format Constants:

• NF90_CLOBBER (default) - CDF-1 format (2GB limits, no format flag needed)
• NF90_64BIT_OFFSET - CDF-2 format (4GB variable limit)
• NF90_64BIT_DATA - CDF-5 format (unlimited sizes)
• NF90_NETCDF4 - NetCDF-4/HDF5 format (groups, compression, user types)
• IOR(NF90_NETCDF4, NF90_CLASSIC_MODEL) - HDF5 storage, classic data model
• NF90_CLASSIC_MODEL is only used with NF90_NETCDF4 to restrict to classic data model

Prerequisites:

• f_simple_2D.f90 - Basic file operations
• f_simple_nc4.f90 - NetCDF-4 basics

Related Examples:

• format_variants.c - C equivalent
• f_compression.f90 - NetCDF-4 compression features

Compilation:

gfortran -o f_format_variants f_format_variants.f90 -lnetcdff -lnetcdf

Usage:

./f_format_variants
ls -lh f_format_*.nc

Author

Edward Hartnett, Intelligent Data Design, Inc.

Date

2026

Function/Subroutine Documentation

f_format_variants()

program f_format_variants

populate_file()

subroutine f_format_variants::populate_file

(

integer, intent(in)

ncid

)