NetCDF  4.9.2
Release Notes

Release notes file for the netcdf-c package.

This file contains a high-level description of this package's evolution. Releases are in reverse chronological order (most recent first). Note that, as of netcdf 4.2, the netcdf-c++ and netcdf-fortran libraries have been separated into their own libraries.

4.9.3 - TBD

4.9.2 - March 14, 2023

This is the maintenance release which adds support for HDF5 version 1.14.0, in addition to a handful of other changes and bugfixes.

  • Fix 'make distcheck' error in See Github #????.
  • Update nc-config to remove inclusion from automatically-detected nf-config and ncxx-config files, as the wrong files could be included in the output. This is in support of GitHub #2274.
  • Update H5FDhttp.[ch] to work with HDF5 version 1.13.2 and later. See Github #2635.
  • [Bug Fix] Update DAP code to enable CURLOPT_ACCEPT_ENCODING by default. See Github #2630.
  • [Bug Fix] Fix byterange failures for certain URLs. See Github #2649.
  • [Bug Fix] Fix 'make distcheck' error in See Github #2631.
  • [Enhancement] Update nc-config to remove inclusion from automatically-detected nf-config and ncxx-config files, as the wrong files could be included in the output. This is in support of GitHub #2274.
  • [Enhancement] Update H5FDhttp.[ch] to work with HDF5 version 1.14.0. See Github #2615.

4.9.1 - February 2, 2023

Known Issues

  • A test in the main branch of netcdf-cxx4 is broken by this rc; this will bear further investigation, but not being treated as a roadblock for the release candidate.
  • The new document, netcdf-c/docs/ is in rough-draft form.
  • Race conditions exist in some of the tests when run concurrently with large numbers of processors

What's Changed from v4.9.0 (automatically generated)

New Contributors

Full Changelog:

4.9.1 - Release Candidate 2 - November 21, 2022

Known Issues

  • A test in the main branch of netcdf-cxx4 is broken by this rc; this will bear further investigation, but not being treated as a roadblock for the release candidate.
  • The new document, netcdf-c/docs/ is in rough-draft form.


  • [Bug Fix] Fix a race condition when testing missing filters. See Github #2557.
  • [Bug Fix] Fix some race conditions due to use of a common file in multiple shell scripts . See Github #2552.

4.9.1 - Release Candidate 1 - October 24, 2022

  • [Enhancement][Documentation] Add Plugins Quick Start Guide. See GitHub #2524 for more information.
  • [Enhancement] Add new entries in netcdf_meta.h, NC_HAS_BLOSC and NC_HAS_BZ2. See Github #2511 and Github #2512 for more information.
  • [Enhancement] Add new options to nc-config: --has-multifilters, --has-stdfilters, --has-quantize, --plugindir. See Github #2509 for more information.
  • [Bug Fix] Fix some errors detected in PR 2497. PR #2497 . See Github #2503.
  • [Bug Fix] Split the remote tests into two parts: one for the remotetest server and one for all other external servers. Also add a configure option to enable the latter set. See Github #2491.
  • [Bug Fix] Fix blosc plugin errors. See Github #2461.
  • [Bug Fix] Fix support for reading arrays of HDF5 fixed size strings. See Github #2466.
  • [Bug Fix] Fix some errors detected in PR #2492 . See Github #2497.
  • [Enhancement] Add support for Zarr (fixed length) string type in nczarr. See Github #2492.
  • [Bug Fix] Split the remote tests into two parts: one for the remotetest server and one for all other external servers. Also add a configure option to enable the latter set. See Github #2491.
  • [Bug Fix] Fix support for reading arrays of HDF5 fixed size strings. See Github #2462.
  • [Bug Fix] Provide a default enum const when fill value does not match any enum constant for the value zero. See Github #2462.
  • [Bug Fix] Fix the json submodule symbol conflicts between libnetcdf and the plugin specific netcdf_json.h. See Github #2448.
  • [Bug Fix] Fix quantize with CLASSIC_MODEL files. See Github #2405.
  • [Enhancement] Add --disable-quantize option to configure.
  • [Bug Fix] Fix CMakeLists.txt to handle all acceptable boolean values for -DPLUGIN_INSTALL_DIR. See Github #2430.
  • [Bug Fix] Fix tst_vars3.c to use the proper szip flag. See Github #2421.
  • [Enhancement] Provide a simple API to allow user access to the internal .rc file table: supports get/set/overwrite of entries of the form "key=value". See Github #2408.
  • [Bug Fix] Use env variable USERPROFILE instead of HOME for windows and mingw. See Github #2405.
  • [Bug Fix] Fix the nc_def_var_fletcher32 code in hdf5 to properly test value of the fletcher32 argument. See Github #2403.

4.9.0 - June 10, 2022

  • [Enhancement] Add quantize functions nc_def_var_quantize() and nc_inq_var_quantize() to enable lossy compression. See Github #1548.
  • [Enhancement] Add zstandard compression functions nc_def_var_zstandard() and nc_inq_var_zstandard(). See Github #2173.
  • [Enhancement] Have netCDF-4 logging output one file per processor when used with parallel I/O. See Github #1762.
  • [Enhancement] Improve filter installation process to avoid use of an extra shell script. See Github #2348.
  • [Bug Fix] Get "make distcheck" to work See Github #2343.
  • [Enhancement] Allow the read/write of JSON-valued Zarr attributes to allow for domain specific info such as used by GDAL/Zarr. See Github #2278.
  • [Enhancement] Turn on the XArray convention for NCZarr files by default. WARNING, this means that the mode should explicitly specify "nczarr" or "zarr" even if "xarray" or "noxarray" is specified. See Github #2257.
  • [Enhancement] Update the documentation to match the current filter capabilities See Github #2249.
  • [Enhancement] Update the documentation to match the current filter capabilities. See Github #2249.
  • [Enhancement] Support installation of pre-built standard filters into user-specified location. See Github #2318.
  • [Enhancement] Improve filter support. More specifically (1) add nc_inq_filter_avail to check if a filter is available, (2) add the notion of standard filters, (3) cleanup szip support to fix interaction with NCZarr. See Github #2245.
  • [Enhancement] Switch to tinyxml2 as the default xml parser implementation. See Github #2170.
  • [Bug Fix] Require that the type of the variable in nc_def_var_filter is not variable length. See Github #/2231.
  • [File Change] Apply HDF5 v1.8 format compatibility when writing to previous files, as well as when creating new files. The superblock version remains at 2 for newly created files. Full backward read/write compatibility for netCDF-4 is maintained in all cases. See Github #2176.
  • [Enhancement] Add ability to set dataset alignment for netcdf-4/HDF5 files. See Github #2206.
  • [Bug Fix] Improve UTF8 support on windows so that it can use utf8 natively. See Github #2222.
  • [Enhancement] Add complete bitgroom support to NCZarr. See Github #2197.
  • [Bug Fix] Clean up the handling of deeply nested VLEN types. Marks nc_free_vlen() and nc_free_string as deprecated in favor of ncaux_reclaim_data(). See Github #2179.
  • [Bug Fix] Make sure that netcdf.h accurately defines the flags in the open/create mode flags. See Github #2183.
  • [Enhancement] Improve support for msys2+mingw platform. See Github #2171.
  • [Bug Fix] Clean up the various inter-test dependencies in ncdump for CMake. See Github #2168.
  • [Bug Fix] Fix use of non-aws appliances. See Github #2152.
  • [Enhancement] Added options to suppress the new behavior from Github #2135. The options for cmake and configure are, respectively -DENABLE_LIBXML2 and --(enable/disable)-libxml2. Both of these options defaul to 'on/enabled'. When disabled, the bundled ezxml XML interpreter is used regardless of whether libxml2 is present on the system.
  • [Enhancement] Support optional use of libxml2, otherwise default to ezxml. See Github #2135 – H/T to Egbert Eich.
  • [Bug Fix] Fix several os related errors. See Github #2138.
  • [Enhancement] Support byte-range reading of netcdf-3 files stored in private buckets in S3. See Github #2134
  • [Enhancement] Support Amazon S3 access for NCZarr. Also support use of the existing Amazon SDK credentials system. See Github #2114
  • [Bug Fix] Fix string allocation error in H5FDhttp.c. See Github #2127.
  • [Bug Fix] Apply patches for ezxml and for selected oss-fuzz detected errors. See Github #2125.
  • [Bug Fix] Ensure that internal Fortran APIs are always defined. See Github #2098.
  • [Enhancement] Support filters for NCZarr. See Github #2101
  • [Bug Fix] Make PR 2075 long file name be idempotent. See Github #2094.

4.8.1 - August 18, 2021

  • [Bug Fix] Fix multiple bugs in libnczarr. See Github #2066.
  • [Enhancement] Support windows network paths (e.g. \svc...). See Github #2065.
  • [Enhancement] Convert to a new representation of the NCZarr meta-data extensions: version 2. Read-only backward compatibility is provided. See Github #2032.
  • [Bug Fix] Fix dimension_separator bug in libnczarr. See Github #2035.
  • [Bug Fix] Fix bugs in libdap4. See Github #2005.
  • [Bug Fix] Store NCZarr fillvalue as a singleton instead of a 1-element array. See Github #2017.
  • [Bug Fixes] The netcdf-c library was incorrectly determining the scope of dimension; similar to the type scope problem. See Github #2012 for more information.
  • [Bug Fix] Re-enable DAP2 authorization testing. See Github #2011.
  • [Bug Fix] Fix bug with windows version of mkstemp that causes failure to create more than 26 temp files. See Github #1998.
  • [Bug Fix] Fix ncdump bug when printing VLENs with basetype char. See Github #1986.
  • [Bug Fixes] The netcdf-c library was incorrectly determining the scope of types referred to by nc_inq_type_equal. See Github #1959 for more information.
  • [Bug Fix] Fix bug in use of XGetopt when building under Mingw. See Github #2009.
  • [Enhancement] Improve the error reporting when attempting to use a filter for which no implementation can be found in HDF5_PLUGIN_PATH. See Github #2000 for more information.
  • [Bug Fix] Fix make distcheck issue in nczarr_test/ directory. See Github #2007.
  • [Bug Fix] Fix bug in NCclosedir in dpathmgr.c. See Github #2003.
  • [Bug Fix] Fix bug in ncdump that assumes that there is a relationship between the total number of dimensions and the max dimension id. See Github #2004.
  • [Bug Fix] Fix bug in JSON processing of strings with embedded quotes. See Github #1993.
  • [Enhancement] Add support for the new "dimension_separator" enhancement to Zarr v2. See Github #1990 for more information.
  • [Bug Fix] Fix hack for handling failure of shell programs to properly handle escape characters. See Github #1989.
  • [Bug Fix] Allow some primitive type names to be used as identifiers depending on the file format. See Github #1984.
  • [Enhancement] Add support for reading/writing pure Zarr storage format that supports the XArray _ARRAY_DIMENSIONS attribute. See Github #1952 for more information.
  • [Update] Updated version of bzip2 used in filter testing/functionality, in support of Github #1969.
  • [Bug Fix] Corrected HDF5 version detection logic as described in Github #1962.

4.8.0 - March 30, 2021

  • [Enhancement] Bump the NC_DISPATCH_VERSION from 2 to 3, and as a side effect, unify the definition of NC_DISPATCH_VERSION so it only needs to be defined in CMakeLists.txt and See Github #1945 for more information.
  • [Enhancement] Provide better cross platform path name management. This converts paths for various platforms (e.g. Windows, MSYS, etc.) so that they are in the proper format for the executing platform. See Github #1958 for more information.
  • [Bug Fixes] The nccopy program was treating -d0 as turning deflation on rather than interpreting it as "turn off deflation". See Github #1944 for more information.
  • [Enhancement] Add support for storing NCZarr data in zip files. See Github #1942 for more information.
  • [Bug Fixes] Make fillmismatch the default for DAP2 and DAP4; too many servers ignore this requirement.
  • [Bug Fixes] Fix some memory leaks in NCZarr, fix a bug with long strides in NCZarr. See Github #1913 for more information.
  • [Enhancement] Add some optimizations to NCZarr, dosome cleanup of code cruft, add some NCZarr test cases, add a performance test to NCZarr. See Github #1908 for more information.
  • [Bug Fix] Implement a better chunk cache system for NCZarr. The cache now uses extendible hashing plus a linked list for provide a combination of expandibility, fast access, and LRU behavior. See Github #1887 for more information.
  • [Enhancement] Provide .rc fields for S3 authentication: HTTP.S3.ACCESSID and HTTP.S3.SECRETKEY.
  • [Enhancement] Give the client control over what parts of a DAP2 URL are URL encoded (i.e. xx). This is to support the different decoding rules that servers apply to incoming URLS. See Github #1884 for more information.
  • [Bug Fix] Fix incorrect time offsets from ncdump -t, in some cases when the time units attribute contains both a non-zero time-of-day, and a time zone suffix containing the letter "T", such as "UTC". See Github #1866 for more information.
  • [Bug Fix] Cleanup the NCZarr S3 build options. See Github #1869 for more information.
  • [Bug Fix] Support aligned access for selected ARM processors. See Github #1871 for more information.
  • [Documentation] Migrated the documents in the NUG/ directory to the dedicated NUG repository found at
  • [Bug Fix] Revert the internal filter code to simplify it. From the user's point of view, the only visible change should be that (1) the functions that convert text to filter specs have had their signature reverted and renamed and have been moved to netcdf_aux.h, and (2) Some filter API functions now return NC_ENOFILTER when inquiry is made about some filter. Internally, the dispatch table has been modified to get rid of the complex structures.
  • [Bug Fix] If the HDF5 byte-range Virtual File Driver is available )HDf5 1.10.6 or later) then use it because it has better performance than the one currently built into the netcdf library.
  • [Bug Fix] Fixed byte-range support with cURL > 7.69. See [].
  • [Enhancement] Added new test for using compression with parallel I/O: nc_test4/tst_h_par_compress.c. See [].
  • [Bug Fix] Don't return error for extra calls to nc_redef() for netCDF/HDF5 files, unless classic model is in use. See [].
  • [Enhancement] Added new parallel I/O benchmark program to mimic NOAA UFS data writes, built when –enable-benchmarks is in configure. See [].
  • [Bug Fix] Now allow szip to be used on variables with unlimited dimension [].
  • [Enhancement] Add support for cloud storage using a variant of the Zarr storage format. Warning: this feature is highly experimental and is subject to rapid evolution [].
  • [Bug Fix] Fix nccopy to properly set default chunking parameters when not otherwise specified. This can significantly improve performance in selected cases. Note that if seeing slow performance with nccopy, then, as a work-around, specifically set the chunking parameters. [].
  • [Bug Fix] Fix some protocol bugs/differences between the netcdf-c library and the OPeNDAP Hyrax server. Also cleanup checksum handling [].* [Bug Fix] IMPORTANT: Ncgen was not properly handling large data sections. The problem manifests as incorrect ordering of data in the created file. Aside from examining the file with ncdump, the error can be detected by running ncgen with the -lc flag (to produce a C file). Examine the file to see if any variable is written in pieces as opposed to a single call to nc_put_vara. If multiple calls to nc_put_vara are used to write a variable, then it is probable that the data order is incorrect. Such multiple writes can occur for large variables and especially when one of the dimensions is unlimited.
  • [Bug Fix] Add necessary __declspec declarations to allow compilation of netcdf library without causing errors or (_declspec related) warnings [].
  • [Enhancement] When a filter is applied twice with different parameters, then the second set is used for writing the dataset [].
  • [Bug Fix] Now larger cache settings are used for sequential HDF5 file creates/opens on parallel I/O capable builds; see Github #1716 for more information.
  • [Bug Fix] Add functions to libdispatch/dnotnc4.c to support dispatch table operations that should work for any dispatch table, even if they do not do anything; functions such as nc_inq_var_filter [].
  • [Bug Fix] Fixed a scalar annotation error when scalar == 0; see Github #1707 for more information.
  • [Bug Fix] Use proper CURLOPT values for VERIFYHOST and VERIFYPEER; the semantics for VERIFYHOST in particular changed. Documented in NUG/ See [].
  • [Bug Fix][cmake] Correct an issue with parallel filter test logic in CMake-based builds.
  • [Bug Fix] Now allow nc_inq_var_deflate()/nc_inq_var_szip() to be called for all formats, not just HDF5. Non-HDF5 files return NC_NOERR and report no compression in use. This reverts behavior that was changed in the 4.7.4 release. See [].
  • [Bug Fix] Compiling on a big-endian machine exposes some missing forward delcarations in dfilter.c.
  • [File Change] Change from HDF5 v1.6 format compatibility, back to v1.8 compatibility, for newly created files. The superblock changes from version 0 back to version 2. An exception is when using libhdf5 deprecated versions 1.10.0 and 1.10.1, which can only create v1.6 compatible format. Full backward read/write compatibility for netCDF-4 is maintained in all cases. See Github #951.

4.7.4 - March 27, 2020

4.7.3 - November 20, 2019

4.7.2 - October 22, 2019

  • [Bug Fix][Enhancement] Various bug fixes and enhancements.
  • [Bug Fix][Enhancement] Corrected an issue where protected memory was being written to with some pointer slight-of-hand. This has been in the code for a while, but appears to be caught by the compiler on OSX, under circumstances yet to be completely nailed down. See GitHub #1486 for more information.
  • [Enhancement] [Parallel IO] Added support for parallel functions in MSVC. See Github #1492 for more information.
  • [Enhancement] Added a function for changing the ncid of an open file. This function should only be used if you know what you are doing, and is meant to be used primarily with PIO integration. See GitHub #1483 and GitHub #1487 for more information.

4.7.1 - August 27, 2019

  • [Enhancement] Added unit_test directory, which contains unit tests for the libdispatch and libsrc4 code (and any other directories that want to put unit tests there). Use –disable-unit-tests to run without unit tests (ex. for code coverage analysis). See GitHub #1458.
  • [Bug Fix] Remove obsolete _CRAYMPP and LOCKNUMREC macros from code. Also brought documentation up to date in man page. These macros were used in ancient times, before modern parallel I/O systems were developed. Programmers interested in parallel I/O should see nc_open_par() and nc_create_par(). See GitHub #1459.
  • [Enhancement] Remove obsolete and deprecated functions nc_set_base_pe() and nc_inq_base_pe() from the dispatch table. (Both functions are still supported in the library, this is an internal change only.) See GitHub #1468.
  • [Bug Fix] Reverted nccopy behavior so that if no -c parameters are given, then any default chunking is left to the netcdf-c library to decide. See GitHub #1436.

4.7.0 - April 29, 2019

  • [Enhancement] Updated behavior of pkgconfig and nc-config to allow the use of the --static flags, e.g. nc-config --libs --static, which will show information for linking against libnetcdf statically. See Github #1360 and Github #1257 for more information.
  • [Enhancement] Provide byte-range reading of remote datasets. This allows read-only access to, for example, Amazon S3 objects and also Thredds Server datasets via the HTTPService access method. See GitHub #1251.
  • Update the license from the home-brewed NetCDF license to the standard 3-Clause BSD License. This change does not result in any new restrictions; it is merely the adoption of a standard, well-known and well-understood license in place of the historic NetCDF license written at Unidata. This is part of a broader push by Unidata to adopt modern, standardized licensing.

4.6.3 - February 28, 2019

  • [Bug Fix] Correctly generated netcdf.pc generated either by configure or cmake. If linking against a static netcdf, you would need to pass the --static argument to pkg-config in order to list all of the downstream dependencies. See Github #1324 for more information.
  • Now always write hidden coordinates attribute, which allows faster file opens when present. See Github #1262 for more information.
  • Some fixes for rename, including fix for renumbering of varids after a rename (#1307), renaming var to dim without coordinate var. See Github #1297.
  • Fix of NULL parameter causing segfaults in put_vars functions. See Github #1265 for more information.
  • Fix of –enable-benchmark benchmark tests Github #1211
  • Update the license from the home-brewed NetCDF license to the standard 3-Clause BSD License. This change does not result in any new restrictions; it is merely the adoption of a standard, well-known and well-understood license in place of the historic NetCDF license written at Unidata. This is part of a broader push by Unidata to adopt modern, standardized licensing.
  • [BugFix] Corrected DAP-related issues on big-endian machines. See Github #1321, Github #1302 for more information.
  • [BugFix][Enhancement] Various and sundry bugfixes and performance enhancements, thanks to @edhartnett, @gsjarrdema, @t-b, @wkliao, and all of our other contributors.
  • [Enhancement] Extended nccopy -F syntax to support multiple variables with a single invocation. See Github #1311 for more information.
  • [BugFix] Corrected an issue where DAP2 was incorrectly converting signed bytes, resulting in an erroneous error message under some circumstances. See GitHub #1317 for more information. See Github #1319 for related information.
  • [BugFix][Enhancement] Modified nccopy so that _NCProperties is not copied over verbatim but is instead generated based on the version of libnetcdf used when copying the file. Additionally, _NCProperties are displayed if/when associated with a netcdf3 file, now. See GitHub #803 for more information.

4.6.2 - November 16, 2018

  • [Enhancement] Lazy att read - only read atts when user requests one of them. See GitHub #857.
  • [Enhancement] Fast global att read - when global atts are read, they are read much more quickly. See GitHub #857.

4.6.2-rc2 November 1, 2018

  • [Enhancement] Add nccopy command options for per-variable chunk sizing, and minimum chunk size. See GitHub #1087.
  • [Bug Fix] Fix nccopy handling of user specified chunk sizes. See GitHub #725,#1087.
  • [Bug Fix] Avoid limit on number of times a netCDF4 attribute can be updated. Not a complete fix for the HDF5 "maximum creation order" problem, but should greatly reduce occurrences in many real-world cases. See GitHub #350.
  • [Bug Fix] The use of NC_DISKLESS has been modified to make it cleaner. This adds a new flag called NC_PERSIST that takes over the now obsolete NC_MPIPOSIX.
  • [Obsolete] Obsolete the MPIPOSIX flag.
  • [Bug Fix] When using filters with HDF5 1.10.x or later, it is necessary to utilize the HDF5 replacements for malloc, realloc, and free in the filter code.

4.6.2-rc1 - September 19, 2018

  • [Enhancement] Create a new version of _NCProperties provenance attribute. This version (version 2) supports arbitrary key-value pairs. It is the default when new files are created. Version 1 continues to be accepted.
  • [Enhancement] Allow user to set http read buffersize for DAP2 and DAP4 using the tag HTTP.READ.BUFFERSIZE in the .daprc file.
  • [Enhancement] Allow user to set http keepalive for DAP2 and DAP4 using the tag HTTP.KEEPALIVE in the .daprc file (see the OPeNDAP documentation for details).
  • [Enhancement] Support DAP4 remote tests using a new remote test server located on the Unidata JetStream project.
  • [Enhancement] Improved the performance of the nc_get/put_vars operations by using the equivalent slab capabilities of hdf5. Result is a significant speedup of these operations. See GitHub #1001 for more information.
  • [Enhancement] Expanded the capabilities of NC_INMEMORY to support writing and accessing the final modified memory. See GitHub #879 for more information.
  • [Enhancement] Made CDF5 support enabled by default. See Github #931 for more information.
  • [Bug Fix] Corrected a number of memory issues identified in ncgen. See GitHub #558 for more information.

4.6.1 - March 19, 2018

  • [Bug Fix] Corrected an issue which could result in a dap4 failure. See Github #888 for more information.
  • [Bug Fix][Enhancement] Allow nccopy to control output filter suppresion. See Github #894 for more information.
  • [Enhancement] Reverted some new behaviors that, while in line with the netCDF specification, broke existing workflows. See Github #843 for more information.
  • [Bug Fix] Improved support for CRT builds with Visual Studio, improves zlib detection in hdf5 library. See Github #853 for more information.
  • [Enhancement][Internal] Moved HDF4 into a distinct dispatch layer. See Github #849 for more information.

4.6.0 - January 24, 2018

  • [Enhancement] Full support for using HDF5 dynamic filters, both for reading and writing. See the file docs/
  • [Enhancement] Added an option to enable strict null-byte padding for headers; this padding was specified in the spec but was not enforced. Enabling this option will allow you to check your files, as it will return an E_NULLPAD error. It is possible for these files to have been written by older versions of libnetcdf. There is no effective problem caused by this lack of null padding, so enabling these options is informational only. The options for configure and cmake are --enable-strict-null-byte-header-padding and -DENABLE_STRICT_NULL_BYTE_HEADER_PADDING, respectively. See Github #657 for more information.
  • [Enhancement] Reverted behavior/handling of out-of-range attribute values to pre-4.5.0 default. See Github #512 for more information.
  • [Bug] Fixed error in tst_parallel2.c. See Github #545 for more information.
  • [Bug] Fixed handling of corrupt files + proper offset handling for hdf5 files. See Github #552 for more information.
  • [Bug] Corrected a memory overflow in tst_h_dimscales, see Github #511, Github #505, Github #363 and Github #244 for more information.

4.5.0 - October 20, 2017

  • Corrected an issue which could potential result in a hang while using parallel file I/O. See Github #449 for more information.
  • Addressed an issue with ncdump not properly handling dates on a 366 day calendar. See GitHub #359 for more information.

4.5.0-rc3 - September 29, 2017

  • [Update] Due to ongoing issues, native CDF5 support has been disabled by default. You can use the options mentioned below (--enable-cdf5 or -DENABLE_CDF5=TRUE for configure or cmake, respectively). Just be aware that for the time being, Reading/Writing CDF5 files on 32-bit platforms may result in unexpected behavior when using extremely large variables. For 32-bit platforms it is best to continue using NC_FORMAT_64BIT_OFFSET.
  • [Bug] Corrected an issue where older versions of curl might fail. See GitHub #487 for more information.
  • [Enhancement] Added options to enable/disable CDF5 support at configure time for autotools and cmake-based builds. The options are --enable/disable-cdf5 and ENABLE_CDF5, respectively. See Github #484 for more information.
  • [Bug Fix] Corrected an issue when subsetting a netcdf3 file via nccopy -v/-V. See Github #425 and Github #463 for more information.
  • [Bug Fix] Corrected --has-dap and --has-dap4 output for cmake-based builds. See GitHub #473 for more information.
  • [Bug Fix] Corrected an issue where NC_64BIT_DATA files were being read incorrectly by ncdump, despite the data having been written correctly. See GitHub #457 for more information.
  • [Bug Fix] Corrected a potential stack buffer overflow. See GitHub #450 for more information.

4.5.0-rc2 - August 7, 2017

  • [Bug Fix] Addressed an issue with how cmake was implementing large file support on 32-bit systems. See GitHub #385 for more information.
  • [Bug Fix] Addressed an issue where ncgen would not respect keyword case. See GitHub #310 for more information.

4.5.0-rc1 - June 5, 2017

  • [Enhancement] DAP4 is now included. Since dap2 is the default for urls, dap4 must be specified by

    1. using "dap4:" as the url protocol, or
    2. appending "\#protocol=dap4" to the end of the url, or
    3. appending "\#dap4" to the end of the url

    Note that dap4 is enabled by default but remote-testing is disabled until the testserver situation is resolved.

  • [Enhancement] The remote testing server can now be specified with the --with-testserver option to ./configure.
  • [Enhancement] Modified netCDF4 to use ASCII for NC_CHAR. See Github Pull request #316 for more information.
  • [Bug Fix] Corrected an error with how dimsizes might be read. See Github #410 for more information.
  • [Bug Fix] Corrected an issue where 'make check' would fail if 'make' or 'make all' had not run first. See Github #339 for more information.
  • [Bug Fix] Corrected an issue on Windows with Large file tests. See Github #385 for more information.
  • [Bug Fix] Corrected an issue with diskless file access, see Pull Request #400 and Pull Request #403 for more information.
  • [Upgrade] The bash based test scripts have been upgraded to use a common include file that isolates build specific information.
  • [Upgrade] The bash based test scripts have been upgraded to use a common include file that isolates build specific information.
  • [Refactor] the oc2 library is no longer independent of the main netcdf-c library. For example, it now uses ncuri, nclist, and ncbytes instead of its homegrown equivalents.
  • [Bug Fix] NC_EGLOBAL is now properly returned when attempting to set a global _FillValue attribute. See GitHub #388 and GitHub #389 for more information.
  • [Bug Fix] Corrected an issue where data loss would occur when _FillValue was mistakenly allowed to be redefined. See Github #390, GitHub #387 for more information.
  • [Upgrade][Bug] Corrected an issue regarding how "orphaned" DAS attributes were handled. See GitHub #376 for more information.
  • [Upgrade] Update utf8proc.[ch] to use the version now maintained by the Julia Language project (
  • [Bug] Addressed conversion problem with Windows sscanf. This primarily affected some OPeNDAP URLs on Windows. See GitHub #365 and GitHub #366 for more information.
  • [Enhancement] Added support for HDF5 collective metadata operations when available. Patch submitted by Greg Sjaardema, see Pull request #335 for more information.
  • [Bug] Addressed a potential type punning issue. See GitHub #351 for more information.
  • [Bug] Addressed an issue where netCDF wouldn't build on Windows systems using MSVC 2012. See GitHub #304 for more information.
  • [Bug] Fixed an issue related to potential type punning, see GitHub #344 for more information.
  • [Enhancement] Incorporated an enhancement provided by Greg Sjaardema, which may improve read/write times for some complex files. Basically, linked lists were replaced in some locations where it was safe to use an array/table. See Pull request #328 for more information. - November 21, 2016

  • [Bug] Fixed an issue where ncgen would potentially crash or write incorrect netCDF4 binary data under very specific circumstances. This bug did not affect data written on 32-bit systems or by using the netCDF library; it was specific to ncgen. This would only happen when writing a compound data type containing an 8-byte data type followed by a 4-byte data type and the 4-byte data type was not properly aligned; this would possibly result in incorrect padding. This did not affect 32-bit systems, or data written directly by the library. See GitHub #323 for more information.
  • [Documentation] Updated documentation related to netCDF variable names and DAP2 access to reflect the undefined behavior potentially observed when DAP2 reserved keywords are used as netCDF variable names. See GitHub #308 for more information.
  • [Bug] Fixed an issue with nc_inq_type() not returning proper value in some circumstances. See GitHub #317 for more information.
  • [Bug] Corrected an issue related to test failures when --disable-utilities or -DENABLE_UTILITIES=OFF are specified when building with autotools or cmake, respectively. See GitHub #313 for more information.
  • [Bug][Enhancement] Corrected a behavioral issue with the _NCProperties attribute taking up too much space. See GitHub #300 and GitHub #301 for more information.
  • [Bug] Corrected behavior for nc-config so that, if nf-config is found in system, the proper fortran-related information will be conveyed. See [GitHub #296](] for more information.

4.4.1 - June 28, 2016

  • [File Change] Starting with release 4.4.1, netCDF-4 files are created with HDF5 v1.6 format compatibility, rather than v1.8. The superblock changes from version 2, as was observed in previous netCDF versions, to version 0. This is due to a workaround required to avoid backwards binary incompatibility when using libhdf5 1.10.x or greater. Superblock versions 0 and 2 appear to be forward and backward compatible for netCDF purposes. Other than a different superblock number, the data should remain consistent. See GitHub #250.
  • [Enhancement] Added better error reporting when ncdump/nccopy are given a bad constraint in a DAP url. See GitHub #279 for more information.

4.4.1-RC3 - June 17, 2016

  • [Bug Fix] Misc. bug fixes and improvements.
  • [Bug Fix] Corrected an issue where adding a _FillValue attribute to a variable would result in other attributes being lost. See GitHub #239 for more details.
  • [Bug Fix][Parallel I/O] Corrected an issue reported by Kent Yang at the HDF group related to Collective Parallel I/O and a potential hang.

4.4.1-RC2 - May 13, 2016

  • [Enhancement] Added provenance information to files created. This information consists of a persistent attribute named _NCProperties plus two computed attributes, _IsNetcdf4 and _SuperblockVersion. Associated documentation was added to the file docs/ See GitHub pull request #260 for more information.
  • [Bug Fix] Cleaned up some dead links in the doxygen-generated documentation.
  • [Bug Fix] Corrected several issues related to building under Visual Studio 2014.
  • [Bug Fix] Corrected several test failures related to HDF5 1.10.0
  • [Bug Fix] Reverted SOVersion current to 11 from 12; it was incorrectly incremented in netCDF-C release 4.4.1-RC1.
  • [Enhancement][Windows] Bumped the included libhdf5 to 1.8.16 from 1.8.15 for pre-built Visual Studio installer files.

4.4.1-RC1 - April 15, 2016

  • [Bug Fix][Enhancement] Fixed an issue with netCDF4 files generated using version 1.10.0 of the HDF5 library. The 1.10 release potentially changed the underlying file format, introducing a backwards compatibility issue with the files generated. HDF5 provided an API for retaining the 1.8.x file format, which is now on by default. See GitHub Issue #250 for more information.
  • [Bug Fix] Corrected an issue with autotools-based builds performed out-of-source-tree. See GitHub Issue #242 for more information.
  • [Enhancement] Modified nc_inq_type() so that it would work more broadly without requiring a valid ncid. See GitHub Issue #240 for more information.
  • [Enhancement] Accepted a patch code which added a hashmap lookup for rapid var and dim retrieval in nc3 files, contributed by Greg Sjaardema. See GitHub Pull Request #238 for more information.
  • [Bug Fix] Accepted a contributed pull request which corrected an issue with how the cmake-generated nc-config file determined the location of installed files. See GitHub Pull Request #235 for more information.
  • [Enhancement] Added an advanced option for CMake-based builds, ENABLE_SHARED_LIBRARY_VERSION. This option is ON by default, but if turned off, only libnetcdf.dylib will be generated, instead of files containing the SOVERSION in the file name. This is a requested feature most people might not care about. See GitHub #228 for more information.
  • [Bug Fix] Corrected an issue with duplicated error codes defined in multiple header files. See GitHub #213 for more information.
  • [Bug Fix] Addressed an issue specific to Visual Studio 2015 on Windows. On very large files, some calls to the fstat class of functions would fail for no apparent reason. This behavior was not observed under Visual Studio 2013. This has now been mitigated. See GitHub #188 for more information.
  • [Enhancement] Updated nc-config to report whether logging is enabled in netcdf. Additionally, if f03 is available in an installed netcdf-fortran library, it will now be reported as well.
  • [Bug Fix] Addressed an issue where netcdf_mem.h was not being installed by cmake. See GitHub #227 for more information.
  • [Bug Fix] Addressed an issue where ncdump would crash when trying to read a netcdf file containing an empty ragged VLEN variable in an unlimited dimension. See GitHub #221 for more information.

4.4.0 Released - January 13, 2016

  • Bumped SO version to 11.0.0.
  • Modified CMakeLists.txt to work with the re-organized cmake configuration used by the latest HDF5, 1.8.16, on Windows. Before this fix, netCDF would fail to locate hdf5 1.8.16 when using cmake on Windows. See GitHub #186 for more information.
  • Addressed an issue with ncdump when annotations were used. The indices for the last row suffered from an off-by-1 error. See GitHub issue #181 for more information.
  • Addressed an issue on platforms where char is unsigned by default (such as ARM), as well as an issue describing regarding undefined behavior, again on ARM. See GitHub issue #159 for detailed information.
  • Fixed an ambiguity in the grammar for cdl files. See GitHub #178 for more information.
  • Updated documentation for nc_get_att_string() to reflect the fact that it returns allocated memory which must be explicitly free'd using nc_free_string(). Reported by Constantine Khroulev, see GitHub Issue 171 for more information.
  • Modified ncgen to properly handle the L and UL suffixes for integer constants to keep backward compatibility. Now it is the case the single L suffix (e.g. 111L) is treated as a 32 bit integer. This makes it consistent with the fact that NC_LONG (netcdf.h) is an alias for NC_INT. Existing .cdl files should be examined for occurrences of the L prefix to ensure that this change will not affect them. (see Github issue 156[]).
  • Updated documentation to reference the new NodeJS interface to netcdf4, by Sven Willner. It is available from or from the GitHub repository at
  • Incorporated pull request from Greg Sjaardema to remove the internal hard-wired use of NC_MAX_DIMS, instead using a dynamic memory allocation.

4.4.0-RC5 Released - November 11, 2015

4.4.0-RC4 Released - November 10, 2015

  • Added CDM-5 support via new mode flag called NC_64BIT_DATA (alias NC_CDF5).

    Major kudos to Wei-Keng Liao for all the effort he put into getting this to work.

    This cascaded into a number of other changes.

    1. Renamed libsrcp5 -> libsrcp because PnetCDF can do parallel io for CDF-1, CDF-2 and CDF-5, not just CDF-5.
    2. Given #1, then the NC_PNETCDF mode flag becomes a subset of NC_MPIIO, so made NC_PNETCDF an alias for NC_MPII.
    3. NC_FORMAT_64BIT is now deprecated. Use NC_FORMAT_64BIT_OFFSET.

Further information regarding the CDF-5 file format specifrication may be found here:

  • Modified to provide finer control over parallel support. Specifically, add flags for:
    1. HDF5_PARALLEL when hdf5 library has parallel enabled
    2. –disable-parallel4 to be used when we do not want netcdf-4 to use parallelism even if hdf5 has it enabled.
  • Deprecating various extended format flags.

The various extended format flags of the format NC_FORMAT_FOO have been refactored into the form NC_FORMATX_FOO. The old flags still exist but have been marked as deprecated and will be removed at some point. This was done to avoid confusion between the extended format flags and the format flags NC_FORMAT_CLASSIC, NC_FORMAT_64BIT_OFFSET, etc. The mapping of deprecated-to-new flags is as follows:

Deprecated Replaced with
  • Reduced minimum cmake version to 2.8.11 from 2.8.12. This will allow for cmake use on a broader set of popular linux platforms without having to do a custom cmake install. See for more information.
  • The documentation section The Default Chunking Scheme has been updated with more information. This lives in the guide.dox file in the docs/ directory, or can be found online in the appropriate location (typically, once this release has been published.

4.4.0-RC3 2015-10-08

  • Addressed an inefficiency in how bytes would be swapped when converting between LITTLE and BIG ENDIANNESS. See NCF-338 for more information.
  • Addressed an issue where an interrupted read on a POSIX system would return an error even if errno had been properly set to EINTR. This issue was initially reported by David Knaak at Cray. More information may be found at NCF-337.
  • Added a note to the install directions pointing out that parallel make cannot be used for 'make check'.

4.4.0-RC2 Released 2015-07-09

  • Minor bug fixes and cleanup of issues reported with first release candidate.

4.4.0-RC1 Released 2015-06-09

  • The pre-built Windows binaries are now built using Visual Studio 2012, instead of Visual Studio 2010. Source-code compilation remains function with Visual Studio 2010, this is just a change in the pre-built binaries.
  • Added support for opening in-memory file content. See include/netcdf_mem.h for the procedure signature. Basically, it allows one to fill a chunk of memory with the equivalent of some netCDF file and then open it and read from it as if it were any other file. See NCF-328 for more information.
  • Addressed an issue when reading hdf4 files with explicit little-endian datatypes. This issue was reported by Tim Burgess at GitHub. See NCF-332 for more information.
  • Addressed an issue with IBM's XL C compiler on AIX and how it handled some calls to malloc. Also, as suggested by Wolfgang Hayek, developers using this compiler may need to pass CPPFLAGS=-D_LINUX_SOURCE_COMPAT to avoid some test failures.
  • Addressed an issure in netcdf4 related to specifying an endianness explicitly. When specifying an endianness for NC_FLOAT, the value would appear to not be written to file, if checked with ncdump -s. The issue was more subtle; the value would be written but was not being read from file properly for non-NC_INT. See GitHub Issue or NCF-331 for more information.
  • Addressed an issue in netcdf4 on Windows w/DAP related to how byte values were copied with sscanf. Issue originally reported by Ellen Johnson at Mathworks, see NCF-330 for more information.
  • Addressed in issue in netcdf4 files on Windows, built with Microsoft Visual Studio, which could result in a memory leak. See NCF-329 for more information.
  • Addressed an issue in netcdf4 files where writing unlimited dimensions that were not declared at head of the dimensions list, as reported by Ellen Johnson at Mathworks. See NCF-326 for more information.
  • Added an authorization reference document as oc2/ocauth.html.
  • Fixed bug resulting in segmentation violation when trying to add a _FillValue attribute to a variable in an existing netCDF-4 file defined without it (thanks to Alexander Barth). See NCF-187 for more information. Released 2015-02-25

  • Fixed a bug related to renaming the attributes of coordinate variables in a subgroup. See NCF-325 for more information.

4.3.3 Released 2015-02-12

  • Fixed bug resulting in error closing a valid netCDF-4 file with a dimension and a non-coordinate variable with the same name. NCF-324
  • Enabled previously-disabled shell-script-based tests for Visual Studio when bash is detected.

4.3.3-rc3 Released 2015-01-14

  • Added functionality to make it easier to build netcdf-fortran as part of the netcdf-c build for NON-MSVC builds. This functionality is enabled at configure time by using the following Highly Experimental options:
    • Autotools: --enable-remote-fortran-bootstrap

Details are as follows:

Enabling these options creates two new make targets:

  • build-netcdf-fortran
  • install-netcdf-fortran

Example Work Flow from netcdf-c source directory:

  • $ ./configure --enable-remote-fortran-bootstrap --prefix=$HOME/local
  • $ make check
  • $ make install
  • $ make build-netcdf-fortran
  • $ make install-netcdf-fortran

These make targets are only valid after make install has been invoked. This cannot be enforced rigidly in the makefile for reasons we will expand on in the documentation, but in short: make install may require sudo, but using sudo will discard environmental variables required when attempting to build netcdf-fortran in this manner.

It is important to note that this is functionality is for convenience only. It will remain possible to build netcdf-c and netcdf-fortran manually. These make targets should hopefully suffice for the majority of our users, but for corner cases it may still be required of the user to perform a manual build. NCF-323


  • Added a failure state if the m4 utility is not found on non-Windows systems; previously, the build would fail when it reached the point of invoking m4.
  • Added an explicit check in the build systems (autotools, cmake) for the CURL-related option CURLOPT_CHUNK_BGN_FUNCTION. This option was introduced in libcurl version 7.21.0. On installations which require libcurl and have this version, CURLOPT_CHUNK_BGN_FUNCTION will be available. Otherwise, it will not.
  • The PnetCDF support was not properly being used to provide mpi parallel io for netcdf-3 classic files. The wrong dispatch table was being used. NCF-319
  • In nccopy utility, provided proper default for unlimited dimension in chunk-size specification instead of requiring explicit chunk size. Added associated test. NCF-321
  • Fixed documentation typo in FILL_DOUBLE definition in classic format specification grammar. Fixed other typos and inconsistencies in Doxygen version of User Guide.
  • For nccopy and ncgen, added numeric options (-3, -4, -6, -7) for output format, to provide less confusing format version specifications than the error-prone equivalent -k options (-k1, -k2, -k3, -k4). The new numeric options are compatible with NCO's mnemonic version options. The old -k numeric options will still be accepted but are deprecated, due to easy confusion between format numbers and format names. NCF-314
  • Fixed bug in ncgen. When classic format was in force (k=1 or k=4), the "long" datatype should be treated as int32. Was returning an error. NCF-318
  • Fixed bug where if the netCDF-C library is built with the HDF5 library but without the HDF4 library and one attempts to open an HDF4 file, an abort occurs rather than returning a proper error code (NC_ENOTNC). NCF-317
  • Added a new option, NC_EXTRA_DEPS, for cmake-based builds. This is analogous to LIBS in autotools-based builds. Example usage:

    $ cmake .. -NC_EXTRA_DEPS="-lcustom_lib"

More details may be found at the Unidata JIRA Dashboard. NCF-316

4.3.3-rc2 Released 2014-09-24

  • Fixed the code for handling character constants in datalists in ncgen. Two of the problems were:
    1. It failed on large constants
    2. It did not handle e.g. var = 'a', 'b', ... in the same way that ncgen3 did. See NCF-309.
  • Added a new file, netcdf_meta.h. This file is generated automatically at configure time and contains information related to the capabilities of the netcdf library. This file may be used by projects dependent upon netcdf to make decisions during configuration, based on how the netcdf library was built. The macro NC_HAVE_META_H is defined in netcdf.h. Paired with judicious use of ifdef's, this macro will indicate to developers whether or not the meta-header file is present. See NCF-313.

    > Determining the presence of netcdf_meta.h can also be accomplished by methods common to autotools and cmake-based build systems.

  • Changed Doxygen-generated documentation hosted by Unidata to use more robust server-based searching.
  • Corrected embedded URLs in release notes.
  • Corrected an issue where building with HDF4 support with Visual Studio would fail.

4.3.3-rc1 Released 2014-08-25

  • Added CMake-based export files, contributed by Nico Schlömer. See
  • Documented that ncgen input can come from standard input.
  • Regularized generation of libnetcdf.settings file to make parsing it easier.
  • Fixed ncdump bug for char variables with multiple unlimited dimensions and added an associated test. Now the output CDL properly disambiguates dimension groupings, so that ncgen can generate the original file from the CDL. NCF-310
  • Converted the Manually-maintained FAQ page into markdown and added it to the docs/ directory. This way the html version will be generated when the rest of the documentation is built, the FAQ will be under version control, and it will be in a more visible location, hopefully making it easier to maintain.
  • Bumped minimum required version of cmake to 2.8.12. This was necessitated by the adoption of the new CMAKE_MACOSX_RPATH property, for use on OSX.
  • Jennifer Adams has requested a reversion in behavior so that all dap requests include a constraint. Problem is caused by change in prefetch where if all variables are requested, then no constraint is generated. Fix is to always generate a constraint in prefetch. NCF-308
  • Added a new option for cmake-based builds, ENABLE_DOXYGEN_LATEX_OUTPUT. On those systems with make and pdflatex, setting this option ON will result in pdf versions of the documentation being built. This feature is experimental.
  • Bumped minimum CMake version to 2.8.9 from 2.8.8 as part of a larger pull request contributed by Nico Schlömer. Pull Request #64
  • Replaced the NetCDF Library Architecture image with an updated version from the 2012 NetCDF Workshop slides.
  • Fix HDF4 files to support chunking. NCF-272
  • NetCDF creates a libnetcdf.settings file after configuration now, similar to those generated by HDF4 and HDF5. It is installed into the same directory as the libraries. NCF-303.
  • Renamed man4/ directory to docs/ to make the purpose and contents clearer. See man4 vs. docs #60.
  • Removed redundant variable BUILD_DOCS from the CMake configuration file. See the issue at github: #59.
  • Added missing documentation templates to man4/, to correct an issue when trying to build the local Doxygen-generated documentation. This issue was reported by Nico Schlömer and may be viewed on github. Releases miss Doxygen files #56
  • When the NC_MPIPOSIX flag is given for parallel I/O access and the HDF5 library does not have the MPI-POSIX VFD configured in, the NC_MPIPOSIX flag is transparently aliased to the NC_MPIIO flag within the netCDF-4 library.

4.3.2 Released 2014-04-23

  • As part of an ongoing project, the Doxygen-generated netcdf documentation has been reorganized. The goal is to make the documentation easier to parse, and to eliminate redundant material. This project is ongoing.
  • The oc .dodsrc reader was improperly handling the user name and password entries. NCF-299
  • CTestConfig.cmake has been made into a template so that users may easily specify the location of an alternative CDash-based Dashboard using the following two options:
    • NC_TEST_DROP_SITE - Specify an alternative Dashboard by URL or IP address.
    • NC_CTEST_DROP_LOC_PREFIX - Specify a prefix on the remote webserver relative to the root directory. This lets CTest accommodate dashboards that do not live at the top level of the web server.
  • Return an error code on open instead of an assertion violation for truncated file.
  • Documented limit on number of Groups per netCDF-4 file (32767).

4.3.2-rc2 Released 2014-04-15

  • Cleaned up a number of CMake inconsistencies related to CMake usage, parallel builds.
  • Now passing -Wl,–no-undefined to linker when appropriate.
  • Corrected an issue preventing large file tests from running correctly under Windows.
  • Misc Bug Fixes detected by static analysis.

4.3.2-rc1 Released 2014-03-20

  • Pre-built Windows downloads will now be bundled with the latest (as of the time of this writing) versions of the various dependencies:
    • hdf5: 1.8.12
    • zlib: 1.2.8
    • libcurl: 7.35.0
  • Added a separate flag to enable DAP AUTH tests. These tests are disabled by default. The flags for autotools and CMAKE-based builds are (respectively):
    • –enable-dap-auth-tests
  • Fixed small default chunk size for 1-dimensional record variables. NCF-211
  • Cleaned up type handling in netCDF-4 to fix bugs with fill-values.
  • Corrected "BAIL" macros to avoid infinite loop when logging is disabled and an error occurs.
  • Refactored how types are used for attributes, variables, and committed types, clarifying and categorizing fields in structs, and eliminating duplicated type information between variables and types they use.
  • Made type structure shareable by committed datatypes and variables that use it.
  • Handled string datatypes correctly, particularly for fill value attributes. Expanded testing for string fill values.
  • Simplified iteration of objects in the file when it's opened, tracking fewer objects and using less memory.
  • Enabled netCDF-4 bit-for-bit reproducibility for nccopy and other applications (thanks to Rimvydas Jasinskas and Quincey Koziol) by turning off HDF5 object creation, access, and modification time tracking. NCF-290
  • Addressed an issue where cmake-based builds would not properly create a pkg-config file. This file is now created properly by cmake. NCF-288
  • Addressed an issue related to old DAP servers. NCF-287
  • Modified nc_{get/put}_vars to no longer use nc_get/put_varm. They now directly use nc_get/put_vara directly. This means that nc_get/put_vars now work properly for user defined types as well as atomic types. NCF-228 Released 2014-02-05

This is a bug-fix-only release for version 4.3.1.

  • Corrected a DAP issue reported by Jeff Whitaker related to non-conforming servers.
  • Corrected an issue with DAP tests failing in a 64-bit Cygwin environment. NCF-286

4.3.1 Released 2014-01-16

  • Add an extended format inquiry method to the netCDF API: nc_inq_format_extended. NC_HAVE_INQ_FORMAT_EXTENDED is defined in netcdf.h NCF-273

4.3.1-rc6 Released 2013-12-19

  • Fixed fill value handling for string types in nc4_get_vara().
  • Corrected behavior of nc_inq_unlimdim and nv_inq_unlimdims to report dimids in same order as nc_inq_dimids.
  • Addressed an issue reported by Jeff Whitaker regarding nc_inq_nvars returning an incorrect number of dimensions (this issue was introduced in 4.3.1-rc5). Integrated a test contributed by Jeff Whitaker.
  • A number of previously-disabled unit tests were reviewed and made active.

4.3.1-rc5 Released 2013-12-06

  • When opening a netCDF-4 file, streamline the iteration over objects in the underlying HDF5 file.
  • Fixed netCDF-4 failure when renaming a dimension and renaming a variable using that dimension, in either order. NCF-177
  • When compiling with hdf4 support, both autotools and cmake-based builds now properly look for the libjpeg dependency and will link against it when found (or complain if it's not). Also added ENABLE_HDF4_FILE_TESTS option to CMake-based builds.
  • Fixed bug in ncgen; it was not properly filling empty string constants ("") to be the proper length. NCF-279
  • Fixed bug in ncgen where it was interpreting int64 constants as uint64 constants. NCF-278
  • Fixed bug in handling Http Basic Authorization. The code was actually there but was not being executed. NCF-277
  • Added hack to the DAP code to address a problem with the server. That server does not serve up proper DAP2 DDS replies. The Dataset {...} name changes depending on if the request has certain kinds of constraints. NCF-276
  • Fixed bugs with ncdump annotation of values, using -b or -f options. NCF-275

4.3.1-rc4 Released 2013-11-06

  • Addressed an issue on Windows where fstat would report an incorrect file size on files > 4GB. NCF-219
  • Added better documentation about accessing ESG datasets. See
  • Corrected an issue with CMake-based builds enabling HDF4 support where the HDF4 libraries were in a non-standard location.
  • Fix bug introduced by NCF-267 where octal constants above '\177' were not recognized as proper octal constants. NCF-271
  • Fixed an issue where the netcdf.3 man page was not being installed by CMake-based builds. Github

4.3.1-rc3 Released 2013-09-24

  • Modify ncgen to support NUL characters in character array constants. NCF-267
  • Modify ncgen to support disambiguating references to an enum constant in a data list. NCF-265
  • Corrected bug in netCDF-4 dimension ID ordering assumptions, resulting in access that works locally but fails through DAP server. NCF-166
  • Added a new configuration flag, NC_USE_STATIC_CRT for CMake-based Windows builds. The default value is 'OFF'. This will allow the user to define whether to use the shared CRT libraries (\MD) or static CRT libraries (\MT) in Visual Studio builds.
  • Ensure netCDF-4 compiles with OpenMPI as an alternative to MPICH2. NCF-160
  • Addressed issue with hanging Parallel netCDF-4 using HDF5 1.8.10. NCF-240
  • Addressed issue with Large File Support on Windows, using both 32 and 64-bit builds. NCF-219
  • Removed deprecated directories:
    • librpc/
    • udunits/
    • libcf/
    • libcdmr/

4.3.1-rc2 Released 2013-08-19

  • Added configure and accompanying configuration files/templates to release repository. These will only be added to tagged releases on GitHub.
  • Integrated a fix by Quincey Koziol which addressed a variation of NCF-250, Fix issue of netCDF-4 parallel independent access with unlimited dimension hanging.
  • Integrated change contributed by Orion Poplawski which integrated GNUInstallDirs into the netCDF-C CMake system; this will permit systems that install into lib64 (such as Fedora) to make install without problem.
  • Corrected an error with the CMake config files that resulted in the netcdf.3 manpage not being built or installed.

4.3.1-rc1 Released 2013-08-09

  • Migrated from the netCDF-C subversion repository to a publicly available GitHub repository available at This repository may be checked out (cloned) with the following command:

    $ git clone

  • Note: in this release, it is necessary to generate the configure script and makefile templates using autoreconf in the root netCDF-C directory.:

    $ autoreconf -i -f

  • Added nc_rename_grp to allow for group renaming in netCDF-4 files. NCF-204
  • Added a NC_HAVE_RENAME_GRP macro to netcdf.h, as per a request by Charlie Zender. This will allow software compiling against netcdf to easily query whether or not nc_rename_grp() is available.
  • Added Greg Sjaardema's contributed optimization for the nc4_find_dim_len function in libsrc4/nc4internal.c. The patch eliminates several malloc/free calls that exist in the original coding.
  • Added support for dynamic loading, to compliment the dynamic loading support introduced in hdf 1.8.11. Dynamic loading support depends on libdl, and is enabled as follows: NCF-258
    • autotools-based builds: –enable-dynamic-loading
    • cmake-based builds: -DENABLE_DYNAMIC_LOADING=ON
  • Fix issue of netCDF-4 parallel independent access with unlimited dimension hanging. Extending the size of an unlimited dimension in HDF5 must be a collective operation, so now an error is returned if trying to extend in independent access mode. NCF-250
  • Fixed bug with netCDF-4's inability to read HDF5 scalar numeric attributes. Also allow, in addition to zero length strings, a new NULL pointer as a string value. to improve interoperability with HDF5. This required a new CDL constant, 'NIL', that can be output from ncdump for such a string value in an HDF5 or netCDF-4 file. The ncgen utility was also modified to properly handle such NIL values for strings. NCF-56
  • Parallel-build portability fixes, particularly for OpenMPI and gcc/gfortran-4.8.x on OSX.
  • Fix contributed by Nath Gopalaswamy to large file problem reading netCDF classic or 64-bit offset files that have a UINT32_MAX flag for large last record size of a variable that has values larger than 1 byte. This problem had previously been fixed for writing such data, but was only tested with an ncbyte variable.
  • Fixed various minor documentation problems.

4.3.0 Released 2013-04-29

  • fsync: Changed default in autotools config file; fsync must now be explicitly enabled instead of explicitly disabled. NCF-239
  • Fixed netCDF-4 bug where odometer code for libdap2 mishandled stride > 1. Bug reported by Ansley Manke. NCF-249
  • Fixed netCDF-4 bug so netCDF just ignores objects of HDF5 reference type in the file, instead of rejecting the file. NCF-29
  • Fixed netCDF-4 bug with particular order of creation of dimensions, coordinate variables, and subgroups resulting in two dimensions with the same dimension ID. NCF-244
  • Fixed netCDF-4 bug with a multidimensional coordinate variable in a subgroup getting the wrong dimension IDs for its dimensions. NCF-247
  • Fixed bug with incorrect fixed-size variable offsets in header getting written when schema changed for files created by PnetCDF Thanks to Wei-keng Liao for developing and contributing the fix. NCF-234
  • Fixed bug in handling old servers that do not do proper Grid to Structure conversions. NCF-232
  • Replaced the oc library with oc2.0
  • Fix bug with nc_get_var1_uint() not accepting unsigned ints larger than 2**31. NCF-226
  • Fix to convert occurrences of '/' in DAP names to %2f. NCF-223
  • Fix bug in netCDF-4 with scalar non-coordinate variables with same name as dimensions. NCF-222
  • Fix bug in which calling netCDF-4 functions in which behavior that should not depend on order of calls sometimes produces the wrong results. NCF-217
  • Merged in nccopy additions from Martin van Driel to support -g and -v options for specifying which groups or variables are to be copied. NCF-216
  • Merged in PnetCDF bugs fixes from Greg Sjaardema. NCF-214
  • Modify ncgen so that if the incoming file has a special attribute, then it is used to establish the special property of the netcdf file, but the attribute is not included as a real attribute in the file. NCF-213.
  • Added library version info to the user-agent string so that the server logs will be more informative. NCF-210
  • Added work around for bad servers that sometimes sends DAP dataset with duplicate field names. NCF-208
  • Fixed bug with strided access for NC_STRING type. NCF-206
  • Prevented adding an invalid _FillValue attribute to a variable (with nonmatching type or multiple values), to avoid later error when any record variable is extended. NCF-190
  • Fix bug in which some uses of vlen within compounds causes HDF5 errors. NCF-155
  • Fixed ncdump bug in display of data values of variables that use multiple unlimited dimensions. NCF-144
  • Fix bug in which interspersing def_var calls with put_var calls can lead to corrupt metadata in a netCDF file with groups and inherited dimensions. NCF-134
  • Building shared libraries works with DAP and netCDF4 functionality. NCF-205
  • 32-and-64-bit builds are working under MinGW on Windows. NCF-112
  • Config.h for Windows compiles are included in the build. NCF-98
  • NetCDF-4 dependency on NC_MAX_DIMS has been removed. NCF-71
  • 64-bit DLL's are produced on Windows. NCF-65
  • DLL Packaging issues are resolved. NCF-54
  • The CMake build system (with related ctest and cdash systems for testing) has been integrated into netCDF-C. This allows for Visual Studio-based builds in addition to gcc-based builds. This requires at least CMake version 2.8.8. This replaces/supplements the cross-compiled set of Visual-Studio compatible netCDF libraries introduced in netCDF 4.2.1-rc1. Released 2012-08-03

  • Patched libdap2/ncdap3.c to fix DAP performance bug remotely accessing large files (> 2GiB).
  • Patched ncdump/dumplib.c to properly escape special characters in CDL output from ncdump for netCDF-4 string data.

4.2.1 Released 2012-07-18

  • Added a specific NC_MMAP mode flag to modify behavior of NC_DISKLESS.
  • Changed the file protections for NC_DISKLESS created files to 0666 [NCF-182]
  • Fixed ncdump to report error when an unsupported option is specified. [NCF-180]
  • Fixed documentation of CDL char constants in Users Guide and ncgen man page.
  • Fixed memory leak detected by valgrind in one of the HDF5 tests.
  • Fixed problem with #elif directives in posixio.c revealed by PGI compilers.

4.2.1-rc1 Released 2012-06-18

  • Ported static and shared libraries (DLL's) for both 32- and 64-bit Windows, including support for DAP remote access, with netCDF-3 and netCDF-4/HDF5 support enabled. The environment for this build is MSYS/MinGW/MinGW64, but the resulting DLLs may be used with Visual Studio. NCF-112 NCF-57
  • Implemented diskless files for all netCDF formats. For nc_create(), diskless operation performs all operations in memory and then optionally persists the results to a file on close. For nc_open(), but only for netcdf classic files, diskless operation caches the file in-memory, performs all operations on the memory resident version and then writes all changes back to the original file on close. [NCF-110][NCF-109][NCF-5]
  • Added MMAP support. If diskless file support is enabled, then it is possible to enable implementation of diskless files using the operating system's MMAP facility (if available). The enabling flag is "--enable-mmap". This is most useful when using nc_open() and when only parts of files, a single variable say, need to be read.
  • Added configure flag for –disable-diskless.
  • Added nccopy command-line options to exploit diskless files, resulting in large speedups for some operations, for example converting unlimited dimension to fixed size or rechunking files for faster access. Upgraded doxygen and man-page documentation for ncdump and nccopy utilities, including new -w option for diskless nccopy, with an example.
  • Modified Makefile to allow for concurrent builds and to support builds outside the source tree, e.g. 'mkdir build; cd build; SOURCE-DIR/configure' where SOURCE-DIR is the top-level source directory.
  • Fixed some netCDF-4 bugs with handling strings in non-netCDF-4 HDF5 files. [NCF-150]
  • Fixed bug using nccopy to compress with shuffling that doesn't compress output variables unless they were already compressed in the input file. [NCF-162]
  • Fixed bug in 64-bit offset files with large records, when last record variable requires more than 2**32 bytes per record. [NCF-164]
  • Fix bug in which passing a NULL path to nc_open causes failure. [NCF-173]
  • Fixed ncgen bugs in parsing and handling opaque data.
  • Fixed ncdump bug, not escaping characters special to CDL in enumeration labels. [NCF-169]
  • Fixed bug reading netCDF int into a C longlong or writing from longlong to external int on 32-bit platforms with classic format files. The upper 32 bits of the longlong were not cleared on read or used on write. [NCF-171]
  • Resolved some erroneous returns of BADTYPE errors and RANGE errors due to conflating C memory types with external netCDF types when accessing classic or 64-bit offset files. [NCF-172]
  • Fixed bug with ncdump -t interpreting unit attribute without base time as a time unit. [NCF-175]
  • Changed port for testing remote access test server to increase reliability of tests.
  • Modified ncio mechanism to support multiple ncio packages, so that it is possible to have e.g. posixio and memio operating at the same time.
  • Generation of documentation is disabled by default. Use –enable-doxygen to generate. [NCF-168]
  • Added description of configure flags to installation guide.
  • Clarified documentation of arguments to nc**open() and nc**create() and their default values.
  • Fixed doxygen installation guide source file to preserve line breaks in code and scripts. [NCF-174]
  • Cleaned up a bunch of lint issues (unused variables, etc.) and some similar problems reported by clang static analysis.
  • Updated and fixed pkg-config source file to work with separated netCDF language-specific packages. Also fixed nc-config to call nf-config, ncxx-config, and ncxx4-config for for backward compatibility with use of nc-config in current Makefiles. [NCF-165] [NCF-179]

4.2.0 2012-05-01

  • Completely rebuilt the DAP constraint handling. This primarily affects users who specify a DAP constraint as part of their URL. [NCF-120]
  • Fixed cause of slow nccopy performance on file systems with many records and large disk block size or many record variables, by accessing data a record at a time instead of a variable at a time. [NCF-142]
  • Performance improvement to DAP code to support fetching partial variables into the cache; especially important when using nc_get_var() API. A partial variable is one that has ranges attached to the projection variables (e.g. x[1:10][20:21]) [NCF-157]
  • Separate the Fortran and C++ libraries and release the C library and ncdump/ncgen/nccopy without Fortran or C++. [NCF-24]
  • Documentation mostly migrated to Doxygen, from Texinfo. [NCF-26]
  • Properly convert vara start/count parameters to DAP [NCF-105][NCF-106]
  • Fixed major wasted space from previous default variable chunk sizes algorithm. [NCF-81]
  • Fixed bug in nccopy, in which compression and chunking options were ignored for netCDF-4 input files. [NCF-79]
  • Fixed bug in ncgen in which large variables (more than 2**18 elements) duplicates the first 2**18 values into subsequent chunks of data [NCF-154].
  • Applied Greg Sjaardema's nccopy bug fix, not compressing output variables f they were not already using compression on the input file when shuffle specified. [NCF-162]
  • Fixed problem when a URL is provided that contains only a host name. [NCF-103]
  • Fixed behavior of ncgen flags so that -o => -lb and, in the absence of any other markers, make the default be -k1 [NCF-158]
  • Created a text INSTALL file for netCDF-4.2 release. [NCF-161]
  • Fixed bug in ncgen for vlen arrays as fields of compound types where datalists for those types was improperly interpreted [NCF-145] (but see NCF-155).
  • Improve use of chunk cache in nccopy utility, making it practical for rechunking large files. [NCF-85]
  • Fixed nccopy bug copying a netCDF-4 file with a chunksize for an unlimited dimension that is larger than the associated dimension size. [NCF-139]
  • Fixed nccopy bug when rechunking a netCDF-4 file with a chunkspec option that doesn't explicitly specify all dimensions. [NCF-140]
  • Fixed bug in netCDF-4 files with non-coordinate variable with the same name as a dimension. [NCF-141]
  • Incorporated Wei Huang's fix for bug where netCDF-4 sometimes skips over too many values before adding fill values to an in-memory buffer. [NCF-143]
  • Fixed ncgen bug with netCDF-4 variable-length constants (H/T to Lynton Appel). [NCF-145]
  • Incorporated Peter Cao's performance fixes using HDF5 link iterator for any group with many variables or types. [NCF-148]
  • Incorporated Constantine Khroulev's bug fix for invalid usage of MPI_Comm_f2c in nc_create_par. [NCF-135]
  • Fixed turning off fill values in HDF5 layers when NOFILL mode is set in netCDF-4 API (thanks to Karen Schuchardt). [NCF-151]
  • Fixed bug with scalar coordinate variables in netCDF-4 files, causing failure with –enable-extra-tests [NCF-149]
  • Cleaned up the definition and use of nulldup. [NCF-92][NCF-93][NCF-94]
  • Fixed various '#include' bugs. [NCF-91][NCF-96][NCF-127]
  • v2 API functions modified to properly call the external API instead of directly calling the netcdf-3 functions. [NCF-100]
  • Fixed problem with 64-bit offset format where writing more than 2**31 records resulted in erroneous NC_EINVALCOORDS error. [NCF-101]
  • Restored original functionality of ncgen so that a call with no flags, only does the syntax check. [NCF-104]
  • Corrected misc. test bugs [NCF-107]
  • Modified ncdump to properly output various new types (ubyte, ushort, uint, int64, and uint64). [NCF-111]
  • Fixed incorrect link flag for szip in [NCF-116]
  • ncdump -t now properly parses ISO "T" separator in date-time strings. [NCF-16]
  • ncdump -t "human time" functionality now available for attributes and bounds variables [NCF-70]
  • In ncdump, add -g option to support selection of groups for which data is displayed. [NCF-11]
  • Now supports bluefire platform [NCF-52]
  • ncdump now properly displays values of attributes of type NC_USHORT as signed shorts [NCF-82]
  • Rename some code files so that there are no duplicate filenames. [NCF-99]
  • Demonstration of netCDF-4 Performance Improvement with KNMI Data [NCF-113]
  • Dimension size in classic model netCDF-4 files now allows larger sizes than allowed for 64-bit offset classic files. [NCF-117]
  • ncdump now reports correct error message when "-x" option specifying NcML output is used on netCDF-4 enhanced model input. [NCF-129]
  • Fixed bug causing infinite loop in ncdump -c of netCDF-4 file with subgroup with variables using inherited dimensions. [NCF-136]

4.1.3 2011-06-17

  • Replace use of –with-hdf5= and other such configure options that violate conventions and causes build problems. Set environment variables CPPFLAGS, LDFLAGS, and LD_LIBRARY_PATH instead, before running configure script. [NCF-20]
  • Detect from configure script when szlib is needed [NCF-21]
  • Fix bug that can silently zero out portions of a file when writing data in nofill mode beyond the end of a file, crossing disk-block boundaries with region to be written while in-memory buffer is in a specific state. This bug was observed disabling fill mode using Lustre (or other large blksize file system) and writing data slices in reverse order on disk. [NCF-22]
  • Fix bug that prevents netCDF-4/HDF5 files created with netCDF-4.1.2 from being read by earlier versions of netCDF or HDF5 versions before 1.8.7. [NCF-23]
  • Fix bug in configure that did not make the search for the xdr library depend on –enable-dap. [NCF-41]
  • Fix ncgen bug that did not use the value of a _Format attribute in the input CDL file to determine the kind of output file created, when not specified by the -k command-line flag. [NCF-42]
  • Fix ncgen bug, not properly handling unsigned longlong parsing. [NCF-43]
  • Fix DAP client code to suppress variables with names such as "x.y", which DAP protocol interprets as variable "y" inside container "x". Such variables will be invisible when accessed through DAP client. [NCF-47]
  • Define uint type for unsigned integer, if not otherwise available. Symptom was compile error involving uint in putget.c. [NCF-49]
  • Fix username+password handling in the DAP client code. [NCF-50]
  • Add test for handling parallel I/O problem from f77 when user forgets to turn on one of the two MPI flags. [NCF-60]
  • Resolved "make check" problems when ifort compiler. Some "make install" problems remain when using MPI and shared libraries. [NCF-61]
  • Fix problem with f90_def_var not always handle deflate setting when compiler was ifort. [NCF-67]
  • Check that either MPIIO or MPIPOSIX flag is set when parallel create or open is called. Also fix examples that didn't set at least one of these flags. [NCF-68]
  • Improve documentation on handling client-side certificates [NCF-48]
  • Document that array arguments, except in varm functions, must point to contiguous blocks of memory. [NCF-69]
  • Get netCDF-4 tests working for DLLs generated with mingw. [NCF-6]
  • Make changes necessary for upgrading to HDF5 1.8.7 [NCF-66]

4.1.3-rc1 2011-05-06

  • Stop looking for xdr if –disable-dap is used.
  • Don't try to run (some) fortran configure tests on machines with no fortran.
  • Allow nccopy to rechunk with chunksizes larger than current dimension lengths.
  • Initial implementation of CDMREMOTE is complete; needs comprehensive testing.

4.1.3-beta1 2011-04-29

  • Fixed szlib not linking bug.
  • Fixed dreaded "nofill bug", lurking in netCDF classic since at least
  1. Writing more than a disk block's worth of data that crossed disk block boundaries more than a disk block beyond the end of file in nofill mode could zero out recently written earlier data that hadn't yet been flushed to disk.
  • Changed setting for H5Pset_libver_bounds to ensure that all netCDF-4 files can be read by HDF5 1.8.x.
  • Merged libncdap3 and libncdap4 into new libdap2 library. The suffix dap2 now refers to the dap protocol. This is in prep for adding dap4 protocol support.
  • Took out –with-hdf5 and related options due to high cost of maintaining this non-standard way of finding libraries.

4.1.2 2011-03-29

  • Changes in build system to support building dlls on cygwin/mingw32.
  • Changes to fix portability problems and get things running on all test platforms.
  • Some minor documentation fixes.
  • Fixed opendap performance bug for nc_get_vars; required adding nc_get_var{s,m} to the dispatch table.
  • Now check for libz in
  • Fixed some bugs and some performance problems with default chunksizes.

4.1.2-beta2 2011-01-11

  • Add "-c" option to nccopy to specify chunk sizes used in output in terms of list of dimension names.
  • Rewrite netCDF-4 attribute put code for a large speedup when writing lots of attributes.
  • Fix nc-config –libs when static dependent libraries are not installed in the same directory as netCDF libraries (thanks to Jeff Whitaker).
  • Build shared libraries by default, requiring separate Fortran library. Static libraries now built only with –disable-shared.
  • Refactor of HDF5 file metadata scan for large speedup in opening files, especially large files.
  • Complete rewrite of the handling of character datalist constants. The heuristics are documented in ncgen.1.
  • Eliminate use of NC_MAX_DIMS and NC_MAX_VARS in ncdump and nccopy, allocating memory as needed and reducing their memory footprint.
  • Add documentation for new nc_inq_path() function.
  • Use hashing to speedup lookups by name for files with lots of dimensions and variables (thanks to Greg Sjaardema).
  • Add options to nccopy to support uniform compression of variables in output, shuffling, and fixing unlimited dimensions. Documented in nccopy.1 man page and User's Guide.

4.1.2-beta1 2010-07-09

  • Fix "ncdump -c" bug identifying coordinate variables in groups.
  • Fix bug in libsrc/posixio.c when providing sizehint larger than default, which then doesn't get used (thanks to Harald Anlauf).
  • Fix netCDF-4 bug caused when doing enddef/redef and then defining coordinate variable out of order.
  • Fixed bug in man4 directory automake file which caused documentation to be rebuilt after make clean.
  • Turned off HDF5 caching when parallel I/O is in use because of its memory use.
  • Refactoring of netCDF code with dispatch layer to decide whether to call netCDF classic, netCDF-4, or opendap version of a function.
  • Refactoring of netCDF-4 memory internals to reduce memory use and end dependence on NC_MAX_DIMS and NC_MAX_NAME.
  • Modified constraint parser to be more compatible with a java version of the parser.
  • Modified ncgen to utilize iterators internally; should be no user visible effect.
  • Fixed two large-file bugs with using classic format or 64-bit offset format and accessing multidimensional variables with more than 2**32 values.

4.1.1 2010-04-01

  • Fixed various build issues.
  • Fixed various memory bugs.
  • Fixed bug for netCDF-4 files with dimensions and coord vars written in different orders, with data writes interspersed.
  • Added test for HDF5-1.8.4 bug.
  • Added new C++ API from Lynton Appel.

4.1 2010-01-30

  • Much better memory leak checking with valgrind.
  • Added per-variable chunk cache control for better performance. Use nc_set_var_chunk_cache / nf_set_var_chunk_cache / nf90_set_var_chunk_cache to set the per-variable cache.
  • Automatically set per-variable chunk cache when opening a file, or creating a variable, so that the cache is big enough for more than one chunk. (Can be overridden by user). Settings may be changed with configure options –max-default-chunk-size and –default-chunks-in-cache.
  • Better default chunks size. Now chunks are sized to fit inside the DEFAULT_CHUNK_SIZE (settable at configure time with –with-default-chunk-size= option.)
  • Added nccopy utility for converting among netCDF format variants or to copy data from DAP servers to netCDF files.
  • The oc library has been modified to allow the occurrence of alias definitions in the DAS, but they will be ignored.
  • The old ncgen has been moved to ncgen3 and ncgen is now the new ncgen4.
  • Modified –enable-remote-tests to be on by default.
  • Fixed the nc_get_varm code as applied to DAP data sources.
  • Added tests for nc-config.
  • Many documentation fixes.
  • Added capability to use the PnetCDF library to perform parallel I/O on classic and 32-bit offset files. Use the NC_PNETCDF mode flag to get parallel I/O for non-netcdf-4 files.
  • Added libcf library to netCDF distribution. Turn it on with configure option –with-libcf.
  • Added capability to read HDF4 files created with the SD (Scientific Data) API.
  • The DAP support was revised to closely mimic the original libnc-dap support.
  • Significantly revised the data handling mechanism in ncgen4 to more closely mimic the output from the original ncgen.
  • Added prototype NcML output capability to ncgen4. It is specified by the -lcml flag.
  • Added capability to read HDF5 files without dimension scales. This will allow most existing HDF5 datasets to be read by netCDF-4.
  • Fixed bug with endianness of default fill values for integer types when variables are created with a non-native endianness and use the default fill value.
  • Significant refactoring of HDF5 type handling to improve performance and handle complicated nesting of types in cross-platform cases.
  • Added UDUNITS2 to the distribution. Use –with-udunits to build udunits along with netcdf.
  • Made changes suggested by HDF5 team to relax creation-order requirement (for read-only cases) which allows HDF5 1.6.x files to be retrofitted with dimension scales, and be readable to netCDF-4.
  • Handle duplicate type names within different groups in ncdump. Fix group path handling in absolute and relative variable names for "-v" option.
  • Added nc-config shell script to help users build netCDF programs without having to figure out all the compiler options they will need.
  • Fixed ncdump -s bug with displaying special attributes for classic and 64-bit offset files.
  • For writers, nc_sync() now calls fsync() to flush data to disk sooner.
  • The nc_inq_type() function now works for primitive types.

4.0.1 2009-03-26

  • Added optional arguments to F90 API to nf90_open/create, nf90_create_var, and nf90_inquire_variable so that all netCDF-4 settings may be accomplished with optional arguments, instead of separate function calls.
  • Added control of HDF5 chunk cache to allow for user performance tuning.
  • Added parallel example program in F90.
  • Changed default chunking to better handle very large variables.
  • Made contiguous the default for fixed size data sets with no filters.
  • Fixed bug in nc_inq_ncid; now it returns NC_ENOGRP if the named group is not found.
  • Fixed man pages for C and F77 so that netCDF-4 builds will result in man pages that document new netCDF-4 functions.
  • Added OPeNDAP support based on a new C-only implementation. This is enabled using –enable-dap option and requires libcurl. The configure script will attempt to locate libcurl, but if it fails, then its location must be specified by the –with-curl option.

4.0.1-beta2 2008-12-26

  • Changed chunksizes to size_t from int.
  • Fixed fill value problem from F77 API.
  • Fixed problems in netcdf-4 files with multi-dimensional coordinate variables.
  • Fixed ncgen to properly handle CDL input that uses Windows line endings ("\r\n"), instead of getting a syntax error.
  • Added "-s" option to ncdump to display performance characteristics of netCDF-4 files as special virtual attributes, such as _Chunking, _DeflateLevel, _Format, and _Endianness.
  • Added "-t" option to ncdump to display times in human readable form as strings. Added code to interpret "calendar" attribute according to CF conventions, if present, in displaying human-readable times.
  • Added experimental version of ncgen4 capable of generating netcdf-4 data files and C code for creating them. In addition, it supports the special attributes _Format, etc.
  • 4.0.1-beta1 2008-10-16
  • Fixed Fortran 90 int64 problems.
  • Rewrote HDF5 read/write code in accordance with performance advice from Kent.
  • Fixed memory leaks in gets/puts of HDF5 data.
  • Fixed some broken tests for parallel I/O (i.e. MPI) builds.
  • Fixed some cross-compile problems.
  • Rewrote code which placed bogus errors on the HDF5 error stack, trying to open non-existent attributes and variables. Now no HDF5 errors are seen.
  • Removed man subdirectory. Now man4 subdirectory is used for all builds.
  • Changed build so that users with access to parallel make can use it.
  • Added experimental support for accessing data through OPeNDAP servers using the DAP protocol (use –enable-opendap to build it).
  • Fixed ncdump bugs with array field members of compound type variables. Fixed ncdump bug of assuming default fill value for data of type unsigned byte.

4.0 2008-05-31

  • Introduced the use of HDF5 as a storage layer, which allows use of groups, user-defined types, multiple unlimited dimensions, compression, data chunking, parallel I/O, and other features. See the netCDF Users Guide for more information.

3.6.3 2008-05-31

  • In ncdump and ncgen, added CDL support for UTF-8 encoding of characters in names and for escaped special chars in names. Made sure UTF-8 names are normalized using NFC rules before storing or comparing.
  • Handle IEEE NaNs and infinities in a platform-independent way in ncdump output.
  • Added support for ARM representation of doubles, (thanks to Warren Turkal).
  • Fixed bug in C++ API creating 64-bit offset files. (See
  • Fixed bug for variables larger than 4 GB. (See
  • Changed the to build either 3.6.x or 4.x build from the same
  • Build now checks gfortran version and handles it cleanly, also Portland Group in Intel fortran, with various configurations.
  • A Fortran file is now created at build time, based on the setting of –disable-v2.
  • Documentation has been fixed in several places.
  • Upgraded to automake 1.10, autoconf 2.62, and libtool 2.2.2.
  • Includes missing Windows Visual Studio build files.
  • Fixed missing include of config.h in a C++ test program.
  • Fixed maintainer-clean in man directory.
  • Fixed –enable-c-only and make check.
  • Fixed behavior when opening a zero-length file.
  • Many portability enhancements to build cleanly on various platforms.
  • Turned on some old test programs which were not being used in the build.

3.6.2 2007-03-05

  • Released.

3.6.2 beta6 2007-01-20

  • Fine tuning of build system to properly handle cygwin, Mingw, and strange configuration issues.
  • Automake 1.10 has a problem with running our tests on MinGW, so I'm switching back to automake 1.9.6 for this release.

3.6.2 beta5 2006-12-30

  • Now netCDF configuration uses autoconf 2.61, and automake 1.10. (Thanks to Ralf Wildenhues for the patches, and all the autotools help in general!)
  • Final major revision of netCDF tutorial before the 3.6.2 release.
  • Now netCDF builds under MinGW, producing a windows DLL with the C and F77 APIs. Use the –enable-shared –enable-dll –disable-cxx –disable-f90 flags to configure. (C++ and F90 have never been built as windows DLLs, but might be in a future release if there is user interest). This has all been documented in the netCDF Porting and Installation Guide.
  • Now extreme numbers (i.e. those close to the limits of their type) can be turned off in nc_test/nf_test, with –disable-extreme-numbers. It is turned off automatically for Solaris i386 systems.
  • Added –enable-c-only option to configure. This causes only the core netCDF-3 C library to be built. It's the same as –disable-f77 –disable-cxx –disable-v2 –disable-utilities.
  • Added –disable-utilities to turn off building and testing of ncgen/ncdump.
  • Fix a long-standing bug in nf90_get_att_text() pointed out by Ryo Furue, to make sure resulting string is blank-padded on return. This is fixed in the Fortran-90 interface, but is impractical to fix in the Fortran-77 interface implemented via cfortran.h.
  • Now large file tests are run if –enable-large-file-tests is used in the configure.
  • For Cray users, the ffio module is used if the –enable-ffio option is passed to configure.
  • Unrolled loops in byte-swapping code used on little-endian platforms to reduce loop overhead. This optimization resulted in a 22% speedup for some applications accessing floats or ints (e.g. NCO utilities ncap and ncbo) and a smaller speedup for shorts or doubles.
  • Added "-k" option to ncdump and ncgen, for identifying and specifying the kind of netCDF file, one of "classic", "64-bit-offset", "hdf5", or "hdf5-nc3". Removed output of kind of netCDF file in CDL comment produced by ncdump.
  • Fixed bug of ncdump seg-faulting if invoked incorrectly with option like "-c" or "-h" but no file name.

3.6.2 beta4 2006-08-15

  • Changed F77/F90 man pages from netcdf.3f and netcdf.3f90 to netcdf_f77.3 and netcdf_f90.3. Also fixed broken install of man pages.
  • Changed configure script so that "-g -O2" is no longer set as CFLAGS, CXXFLAGS, and FFLAGS by default if a GNU compiler is being used. Now nothing is set.
  • Changed configure script so that fortran flag is set in config.h.
  • Updated Installation and Porting Guide, C++ Interface Guide, F77 and F90 Interface Guides.
  • Build with static libraries by default.
  • Added configure option –enable-separate-fortran, which causes the fortran library to be built separately. This is turned on automatically for shared libraries.
  • Improved clarity of error messages.
  • Changed configuration to get cygwin DLL and mingw DLL builds working, for the C library only (i.e. no F77, F90, or C++ APIs).
  • Changed type of ncbyte in C++ interface from unsigned char to signed char, for consistency with C interface. The C++ documentation warned this change would eventually occur.
  • Changed the C++ interface to use only the netCDF-3 C interface instead of the older netCDF-2 C interface. This has the added benefit that on-the-fly numeric conversions are now supported using get methods, for example you can get data of any type as double. When using –disable-v2 flag to configure, the C++ interface can now be built and installed.

3.6.2 beta3 2006-05-24

  • Changed to use default prefix of /usr/local instead of package-based prefix of previous releases of netCDF. Use the –prefix argument to the configure script to override the default.
  • Made separate fortran library file, instead of appending fortran library functions to the C library file, if –enable-separate-fortran is used during configure (it's turned on automatically if –enable-shared is used). If uses, the fortran API users must link to both the C library and the new fortran library, like this: -lnetcdff -lnetcdf
  • Added netCDF examples in C, C++, F77, F90, and CDL. See the examples subdirectory.
  • Added the NetCDF Tutorial.
  • Minor fixes to some of the netCDF documentation.
  • Made it possible to build without V2 API using –disable-v2 from configure.
  • Switched to new build system, with automake and libtool. Now shared libraries are built (as well as static ones) on platforms which support it. For more information about shared libraries, see
  • Fixed ncdump crash that happened when no arguments were used.
  • Fixed for building with gfortran 4.1.0.
  • Important fix for machines whose SIZEOF_SIZE_T != SIZEOF_LONG, such as NEC-SX, thanks to Stephen Leak.
  • Fixed C++ on AIX platform.
  • Fixed 64-bit builds on AIX platform.
  • Removed bad assertion that could be triggered in rare cases when reading a small file.
  • Added comments in v1hpg.c to clarify purpose of each internal function.
  • Make sure filesize is determined in nc_close() after buffers get flushed.
  • Fix long-standing problem resulting in files up to 3 bytes longer than necessary if there is exactly one record variable of type byte, char, or short and if the number of values per record for that variable is not divisible by 4 (or 2 in the case of short). Now the filesize determined from header info by NC_calcsize should be correct in all cases.

3.6.1 2006-01-31

  • Updated installation manual for 3.6.1.
  • Changed installation to try to provide correct compiler flags for compiling in 64-bit mode on Sun, Irix, AIX, and HPUX. (HPUX doesn't work for me, however). Now run configure with –enable-64bit to get a 64 bit compile.
  • Fixed long-standing bug that would cause small netCDF files to be padded on the end with zero bytes to 4096 bytes when they were opened and changed. Now small files should stay small after you change a value.
  • Fixed bug in assertions in putget.c that would only be noticed if you change the manifest constant NC_MAX_DIMS in netcdf.h to be different from NC_MAX_VAR_DIMS.
  • Moved test ftest.F from fortran to nf_test directory, and fixed bug in ftest.F which caused it to return 0 even if tests failed (no tests were failing, however). Also renamed some test output files to make things a little clearer.
  • If open for writing, pad with up to 3 extra zero bytes before close to the correct canonical length, calculated from the header. Previously files could be short due to not padding when writing in NOFILL mode.
  • Doubled arbitrary limits on number of dimensions, variables, attributes, and length of names.
  • Change name of nc_get_format() to nc_inq_format(). Add analogous interfaces for nf_inq_format(), nf90_inquire(), and NcFile::get_format() to f77, f90, and C++ interfaces. Document new function in texinfo files. Add minimal test to nc_test, nf_test.

3.6.1-beta3 2005-02-17

  • Added function nc_get_format(int ncid, int* formatp) that returns either NC_FORMAT_CLASSIC or NC_FORMAT_64BIT for a CDF1 or CDF2 file, respectively.
  • Added test to nc_test that detects whether format version was changed after a file is reopened and define mode is entered.
  • Correctly configure for Intel ifort Fortran compiler on Linux.

3.6.0-p1 2005-02-18

  • Fixed bug that changes CDF2 files to CDF1 files if CDF2 file is reopened for write access and either an attribute is changed or define mode is entered.

3.6.1-beta2 2005-1-6

  • Fixed absoft compile problem. Maybe.

3.6.1-beta1 2005-1-3

  • Fixed Cygwin C++ problem.
  • Fixed large file problem in MS Visual C++.NET environment.
  • More information in installation and porting guide.

3.6.0 2004-12-16

  • Added texinfo source for the documentation.
  • Added large file tests to Windows directory in distribution.
  • Modified win32 visual studio project files so that m4 is no longer required to build netcdf under visual studio.
  • Modified rules.make to use install instead of cp, fixing install problem for cygwin users.
  • Modified configure/install stuff to support HP-UX.
  • Modified configure/install stuff to support G95.
  • In the f90 interface, applied Arnaud Desitter's fixes to correct mismatches between scalar and array arguments, eliminating (legitimate) complaints by the NAGWare f95 compiler. Also fixed bugs introduced in 3.6.0-beta5 in the mapped array interfaces.

3.6.0-beta6 2004-10-05

  • Fixed AIX 64-bit/largefile install problems.
  • Removed FAQ section from netcdf.texi User's Guide, in deference to online version that can be kept up to date more easily.

3.6.0-beta5 2004-10-04

  • Fixed assertion violation on 64-bit platforms when size of last fixed size variable exceeds 2\^32 - 1.
  • Removed another restriction on file size by making record size (derived from other sizes, not part of the format) an off_t instead of a size_t, when an off_t is larger than a size_t. This permits records to be much larger in either classic format or 64-bit-offset format.
  • Incorporated patch from Mathis Rosenhauer to improve performance of Fortran 90 interface for calls to nf90_put_var_TYPE(), nf90_get_var_TYPE(), nf90_put_vara_TYPE(), and nf90_get_vara_TYPE() functions by not emulating them with the corresponding nf90_put_varm_TYPE() and nf90_get_varm_TYPE() calls.
  • Added tests for invalid offsets in classic format when defining multiple large variables.
  • Improved installation ease. Have configure script use Large File Support as a default, if available.
  • Add "extra\_test" as a target for testing Large File Support.

3.6.0-beta3 2004-08-24

  • Upgraded to recent autoconf, changed configure to (hopefully) improve installation. Also added macros to deal with large file systems.
  • Added nf_set_default_format to Fortran interface.
  • Added testing to the set_default_format functions to nc_test and nf_test.
  • Added documentation to the man page for set_default_format functions.
  • Added two new error return codes to C, f77, and f90 interfaces for invalid dimension size and for bad variable size. Made test for max dimension size depend on whether 64-bit offsets used. Fixed bug with dimension sizes between 2\^31 and 2\^32 (for byte variables).
  • Fixed ncdump to properly print dimensions larger than 2\^31.
  • Fixed ncgen to properly handle dimensions between 2\^31 and 2\^32.


  • Added -v2 (version 2 format with 64-bit offsets) option to ncgen, to specify that generated files or generated C/Fortran code should create 64-bit offset files. Also added -x option to ncgen to specify use of no-fill mode for fast creation of large files.
  • Added function to set default create mode to C interface (nc_set_default_create).
  • Added win32 directory, with NET subdirectory to hold .NET port of netCDF. To use, open netcdf.sln with Visual Studio, and do a clean and then a build of either the debug or release builds. Tests will be run as part of the build process. VC++ with managed extensions is required (i.e. VC++.NET).
  • Added windows installer files to build windows binary installs.


  • By incorporating Greg Sjaardema's patch, added support for 64-bit offset files, which remove many of the restrictions relating to very large files (i.e. larger than 2 GB.) This introduces a new data format for the first time since the original netCDF format was introduced. Files in this new 64-bit offset format can't be read by earlier versions of netCDF. Users should continue to use the netCDF classic format unless they need to create very large files.
  • The test suite, nc_test, will now be run twice, once for netCDF classic format testing, and once for 64-bit offset format testing.
  • The implementation of the Fortran-77 interface has been adapted to version 4.3 of Burkhard Burow's "cfortran.h".


  • Added NEC SX specific optimization for NFILL tunable parameter in libsrc/putget.c

Added support for the ifc Fortran-90 compiler creating files "netcdf.d" and "typesizes.d" (instead of ".mod" files).

  • Fixed access to iargc and getarg functions from Fortran-90 for NAG f90 compiler, contributed by Harald Anlauf.

3.5.1 2004-02-03

  • Updated INSTALL.html for Mac OS X (Darwin).
  • Made the installation of the netCDF Fortran-90 module file more robust regarding the name of the file.
  • Added support for eight-byte integers in Fortran90 interface.
  • Increased advisory limits in C netcdf.h and Fortran for maximum number of dimensions, variables, and attributes.
  • Changed C++ declarations "friend NcFile" to "friend class NcFile" in cxx/netcdfcpp.h to conform to standard.
  • Added Dan Schmitt's backward compatible extension to the C++ record interface to work with arbitrary dimension slices.
  • Added C++ documentation note that caller is responsible for deleting pointer returned by Variable::values() method when no longer needed.
  • Made C++ interface more standard; the result may not compile on some old pre-standard C++ compilers.
  • Fixed bug in ncgen when parsing values of a multidimensional char variable that resulted in failure to pad a value with nulls on IRIX.
  • Fixed ncdump bug adding extra quote to char variable data when using -fc or -ff option.
  • Fixed so compiling with -DNO_NETCDF_2 will work for building without backward-compatibility netCDF-2 interfaces.
  • Eliminated use of ftruncate(), because it fails on FAT32 file systems under Linux.
  • Initialized a pointer in putget.m4 (used to generate putget.c) that was involved in uninitialized memory references when nc_test is run under Purify. Two users had reported seeing crashes resulting from this problem in their applications.
  • Reverted pointer initializations in putget.m4, after testing revealed these caused a performance problem, resulting in many extra calls to px_pgin and px_pgout when running nc_test.
  • Added checking of size of "dimids" vector in function nf90_inquire_variable(...) and error-returning if it isn't sufficiently capacious.
  • Added variable index to ncvarget() and ncattinq() error messages and attribute name to ncattinq() error message.
  • Tweaked configure script to work with recent C++ compilers.
  • Fixed a memory leak in C++ interface, making sure NcVar::cur_rec[] gets deleted in NcVar destructor.
  • Reimplemented nc_sync() fix of version 3.5.0 to eliminate performance penalty when synchronization is unnecessary.
  • Changed order of targets in Makefile to build Fortran interface last, as a workaround for problem with make on AIX platforms.

3.5.0 2001-03-23

  • Added Fortran 90 interface.
  • Changed C macro TIMELEN in file cxx/nctst.cpp to TIMESTRINGLEN to avoid clash with macro defined on AIX systems in /usr/include/time.h.
  • Fixed miswriting of netCDF header when exiting define mode. Because the header was always written correctly later, this was only a problem if there was another reader of the netCDF file.
  • Fixed explicit synchronizing between netCDF writer and readers via the nc_sync(), nf_sync(), and ncsync() functions.
  • Fixed a number of bugs related to attempts to support shrinking the header in netCDF files when attributes are rewritten or deleted. Also fixed the problem that nc__endef() did not work as intended in reserving extra space in the file header, since the extra space would be compacted again on calling nc_close().
  • Fixed the "redef bug" that occurred when nc_enddef() or nf_enddef() is called after nc_redef() or nf_redef(), the file is growing such that the new beginning of a record variable is in the next "chunk", and the size of at least one record variable exceeds the chunk size (see netcdf.3 man page for a description of this tuning parameter and how to set it). This bug resulted in corruption of some values in other variables than the one being added.
  • The "\*\*" tuning functions for the Fortran interface, nf**create, nf**open, and nf**enddef, are now documented in the Fortran interface man pages.
  • Add an 'uninstall' target to all the Makefiles. Dave Glowacki dglo@.nosp@m.SSEC.nosp@m..WISC.nosp@m..EDU 199810011851.MAA27335
  • Added support for multiprocessing on Cray T3E. Hooks added by Glenn, but the majority of the work was done at NERSC. Also includes changes to ffio option specification. Patch rollup provided by R. K. Owen rkowe.nosp@m.n@Ne.nosp@m.rsc.G.nosp@m.OV. The following functions are added to the public interface. nc**create_mp() nc**open_mp() nc_set_base_pe() nc_inq_base_pe()
  • Fixed makefile URL for Win32 systems in INSTALL file.
  • Made test for UNICOS system in the configure script case independent.
  • Ported to the following systems: AIX 4.3 (both /bin/xlc and /usr/vac/bin/xlc compilers) IRIX 6.5 IRIX64 6.5
  • Changed the extension of C++ files from ".cc" to ".cpp". Renamed the C++ interface header file "netcdfcpp.h" instead of "netcdf.hh", changing "netcdf.hh" to include "netcdfcpp.h" for backward compatibility.
  • Treat "FreeBSD" systems the same as "BSD/OS" system w.r.t. Fortran and "whatis" database.
  • Corrected manual pages: corrected spelling of "enddef" (was "endef") and ensured that the words "index" and "format" will be correctly printed.
  • Updated support for Fortran-calling-C interface by updating "fortran/cfortran.h" from version 3.9 to version 4.1. This new version supports the Portland Group Fortran compiler (C macro "pgiFortran") and the Absoft Pro Fortran compiler (C macro "AbsoftProFortran").
  • Corrected use of non-integral-constant-expression in specifying size of temporary arrays in file "libsrc/ncx\_cray.c".
  • Added Compaq Alpha Linux workstation example to INSTALL file.
  • Ported cfortran.h to Cygnus GNU Win32 C compiler (gcc for Windows).
  • Fixed bug in ncdump using same CDL header name when called with multiple files.
  • Added new NULL data type NC_NAT (Not A Type) to facilitate checking whether a variable object has had its type defined yet, for example when working with packed values.
  • Fixed use of compile-time macro NO_NETCDF_2 so it really doesn't include old netCDF-2 interfaces, as intended.
  • Ported to MacOS X Public Beta (Darwin 1.2/PowerPC).
  • Fixed C++ friend declarations to conform to C++ standard.
  • Changed INSTALL file to INSTALL.html instead.

3.4 1998-03-09

  • Fixed ncx_cray.c to work on all CRAY systems, not just CRAY1. Reworked USE_IEG, which was incorrect. Reworked short support. Now USE_IEG and otherwise both pass t_ncx.
  • To better support parallel systems, static and malloc'ed scratch areas which were shared in the library were eliminated. These were made private and on the stack where possible. To support this, the macros ALLOC_ONSTACK and FREE_ONSTACK are defined in onstack.h.
  • The buffered i/o system implementation in posixio.c was reimplemented to limit the number and size of read() or write() system calls and use greater reliance on memory to memory copy. This saves a great deal of wall clock time on slow (NFS) filesystems, especially during nc_endef().
  • Added performance tuning "underbar underbar" interfaces nc**open(), nc**create(), and nc__enddef().
  • The 'sizehint' contract between the higher layers and the ncio layer is consistently enforced.
  • The C++ interface has been updated so that the deprecated "nclong" typedef should no longer be required, and casts to nclong no longer necessary. Just use int or long as appropriate. nclong is still supported for backwards compatibility.
  • The ncdump utility now displays byte values as signed, even on platforms where the type corresponding to a C char is unsigned (SGI, for example). Also the ncdump and ncgen utilities have been updated to display and accept byte attributes as signed numeric values (with a "b" suffix) instead of using character constants.
  • In libsrc/error.c:nc_strerror(int), explain that NC_EBADTYPE applies to "\_FillValue type mismatch".
  • Some changes to configure scripts (aclocal.m4), and ncgen/Makefile to support NEC SUPER-UX 7.2.
  • The "usage" messages of ncgen and ncdump include the string returned from nc_inq_libvers().
  • Corrected some casts in the library so that all phases of the arithmetic computing file offsets occurs with "off\_t" type. This allows certain larger netcdf files to be created and read on systems with larger (64bit) off_t.
  • In ncgen, multidimensional character variables are now padded to the length of last dimension, instead of just concatenating them. This restores an undocumented but convenient feature of ncgen under netCDF-2. Also, a syntax error is now reliably reported if the netcdf name is omitted in CDL input.
  • Fortran and C code generated by ncgen for netCDF components whose names contain "-" characters will now compile and run correctly instead of causing syntax errors.
  • The library allows "." characters in names as well as "\_" and "-" characters. A zero length name "" is explicitly not allowed. The ncgen utility will now permit "." characters in CDL names as well.
  • Memory leaks in the C++ interface NcVar::as_*() member functions and NcFile::add_var() member function are fixed. The documentation was fixed where it indicated incorrectly that the library managed value blocks that the user is actually responsible for deleting.
  • he values of the version 2 Fortran error codes have been modified to make the version 2 Fortran interface more backward compatible at the source level.
  • Added support for systems whose Fortran INTEGER*1 and INTEGER*2 types are equivalent to the C "long" type but whose C "int" and "long" types differ. An example of such a system is the NEC SX-4 with the "-ew" option to the f90 compiler (sheesh, what a system!).
  • Fixed Version 2 Fortran compatibility bug: NCVGTG, NCVGGC, NCVPTG, and NCVPGC didn't work according to the Version 2 documentation if the innermost mapping value (i.e. IMAP[1]) was zero (indicating that the netCDF structure of the variable should be used).

3.3.1 1997-06-16

  • One can now inquire about the number of attributes that a variable has using the global variable ID.
  • The FORTRAN interface should now work on more systems. In particular:
  • It should now work with FORTRAN compilers whose "integer*1" datatype is either a C "signed char", "short", or "int" and whose "integer*2" datatype is either a C "short" or "int".
  • It should now work with FORTRAN compilers that are extremely picky about source code formatting (e.g. the NAG f90 compiler).
  • The dependency on the non-POSIX utility m4(1) for generating the C and FORTRAN manual pages has been eliminated.
  • EXTERNAL statements have been added to the FORTRAN include-file "" to eliminate excessive warnings about "unused" variables (which were actually functions) by some compilers (e.g. SunOS 4.1.3's f77(1) version 1.x).
  • Building the netCDF-3 package no longer requires the existence of the Standard C macro RAND_MAX.
  • Fixed an ncdump bug resulting in ncdump reporting Attempt to convert between text & numbers when _FillValue attribute of a character variable set to the empty string "".
  • Made ncgen tests more stringent and fixed various bugs this uncovered. These included bugs in handling byte attributes on platforms on which char is unsigned, initializing scalar character variables in generated C code under "-c" option, interspersing DATA statements with declaration statements in generated Fortran code under "-f" option, handling empty string as a value correctly in generated C and Fortran, and handling escape characters in strings. The Fortran output under the "-f" option was also made less obscure and more portable, using automatic conversion with netCDF-3 interfaces instead of "BYTE", "INTEGER*1", or "INTEGER*2" declarations.
  • Fixed a C++ interface problem that prevented compiling the C++ library with Digital's cxx compiler.
  • Made ncgen "make test" report failure and stop if test resulted in a failure of generated C or Fortran code.
  • The file that you are now reading was created to contain a high-level description of the evolution of the netCDF-3 package.

3.3 1997-05-15

  • The production version of the netCDF-3 package was released.
  • A comparison of the netCDF-2 and netCDF-3 releases can be found in the file COMPATIBILITY.