NEP Example Programs

NEP includes over 55 C and Fortran example programs covering classic NetCDF, NetCDF-4, NcZarr, OPeNDAP remote access, performance tuning, and parallel I/O.

They are companion code for The NetCDF Developer's Handbook: The Authoritative Guide to Writing High-Performance Programs for Scientific Data Management, Second Edition.

See examples/README.md for build instructions and usage details.

Classic NetCDF (examples/classic/, examples/f_classic/)

Both C and Fortran versions provided for all programs.

• quickstart.c / f_quickstart.f90 — Minimal introduction; the simplest starting point
• simple_2D.c / f_simple_2D.f90 — Basic 2D arrays with dimensions and variables
• coord_vars.c / f_coord_vars.f90 — Coordinate variables and named dimensions
• coord.c / f_coord.f90 — Multi-dimensional coordinate systems
• dump_classic_metadata.c / f_dump_classic_metadata.f90 — Reading and printing all metadata
• size_limits.c / f_size_limits.f90 — Classic format size limits and 64-bit offset format
• unlimited_dim.c / f_unlimited_dim.f90 — Unlimited dimensions and record variables
• var4d.c / f_var4d.f90 — 4-dimensional variables

NetCDF-4 (examples/netcdf-4/, examples/f_netcdf-4/)

Both C and Fortran versions provided for all programs.

• simple_nc4.c / f_simple_nc4.f90 — NetCDF-4 file creation basics
• format_variants.c / f_format_variants.f90 — Classic, 64-bit, CDF-5, and NetCDF-4 formats
• compression.c / f_compression.f90 — Deflate and shuffle compression filters
• chunking_performance.c / f_chunking_performance.f90 — Chunking strategies and performance impact
• multi_unlimited.c / f_multi_unlimited.f90 — Multiple independent unlimited dimensions
• user_types.c / f_user_types.f90 — Compound and enum user-defined types
• groups.c / f_groups.f90 — Hierarchical groups and dimension visibility
• dump_nc4_metadata.c / f_dump_nc4_metadata.f90 — Reading and printing NetCDF-4 metadata

NcZarr (examples/nczarr/)

Both C and Fortran versions provided for all programs.

• nczarr_simple.c / f_nczarr_simple.f90 — Local NcZarr create/read/write with file://...#mode=nczarr URLs
• nczarr_chunking.c / f_nczarr_chunking.f90 — Explicit chunk shape with nc_def_var_chunking()
• nczarr_compression.c / f_nczarr_compression.f90 — Deflate + shuffle compression in NcZarr stores
• nczarr_enhanced.c / f_nczarr_enhanced.f90 — Hierarchical groups and multiple unlimited dimensions

OPeNDAP Remote Access (examples/opendap/)

Both C and Fortran versions provided for all programs.

• opendap_simple.c / f_opendap_simple.f90 — Open and read a remote dataset via OPeNDAP URL
• opendap_subset.c / f_opendap_subset.f90 — Read a hyperslab from a remote variable
• opendap_constraint.c / f_opendap_constraint.f90 — Apply constraint expressions to filter remote data

Performance and Compression Benchmarking (examples/performance/)

C only. Built with -DENABLE_BENCHMARKS=ON (CMake) or --enable-benchmarks (Autotools).

• cache_tuning.c — Chunk cache size and slots effect on read performance
• chunking.c — Row-optimized, column-optimized, and balanced chunk shape comparison
• deflate.c — Deflate compression levels 1–9 speed and ratio benchmarking
• lz4.c — LZ4 compression performance vs deflate
• bzip2.c — BZIP2 compression performance vs deflate
• zstandard.c — Zstandard (ZSTD) compression benchmarking
• szip.c — SZIP compression benchmarking
• lossless.c — Lossless compression algorithm comparison
• quantize.c — Quantization for lossy compression and storage reduction
• endianness.c — Byte order effects on I/O performance
• fill_values.c — Fill value storage and read performance

Parallel I/O (examples/parallelIO/)

Built only when parallel tests are enabled (--enable-parallel-tests / -DENABLE_PARALLEL_TESTS=ON).

• square16_par.c / f_square16_par.f90 — MPI-based parallel NetCDF-4 write and read