Editing Fortran (section)

==Modern Fortran==

The language defined by the twenty-first century standards, in particular because of its incorporation of [[object-oriented programming]] support and subsequently [[Coarray Fortran]], is often referred to as 'Modern Fortran', and the term is increasingly used in the literature.<ref>{{cite web |last1=Lionel |first1=Steve |title=Doctor Fortran in "It's a Modern Fortran World" |url=https://stevelionel.com/drfortran/2013/12/30/doctor-fortran-in-its-a-modern-fortran-world/ |website=Intel (was DEC) Fortran forum discussion group |date=December 30, 2013 |publisher=Intel |access-date=April 11, 2022}}</ref>

===Fortran 2003===
''Fortran 2003,'' officially published as ISO/IEC 1539-1:2004, was a major revision introducing many new features.<ref>{{cite web|title=Fortran 2003– Last Working Draft|url=http://www.j3-fortran.org/doc/year/04/04-007.txt|publisher=Gnu.Org|access-date=May 10, 2014}}</ref> A comprehensive summary of the new features of Fortran 2003 is available at the Fortran Working Group ([[ISO/IEC JTC1/SC22]]/WG5) official Web site.<ref>{{cite web |title=WG5 Completes Processing Fortran 2003 and the TR |website=nag.co.uk |date=May 14, 2004 |url=http://www.nag.co.uk/sc22wg5/ |archive-url=https://web.archive.org/web/20040805025908/http://www.nag.co.uk/sc22wg5/ |archive-date=August 5, 2004 |access-date=April 3, 2023 }}. It may also be downloaded as a PDF file at {{cite web |title=The New Features of Fortran 2003 |url=https://wg5-fortran.org/N1551-N1600/N1579.pdf |archive-url=https://web.archive.org/web/20180115012047/https://wg5-fortran.org/N1551-N1600/N1579.pdf |archive-date=January 15, 2018 |url-status=live |access-date=April 3, 2023 }}</ref>

From that article, the major enhancements for this revision include:
* Derived type enhancements: parameterized derived types, improved control of accessibility, improved structure constructors, and finalizers
* [[Object-oriented programming]] support: type extension and [[Inheritance (object-oriented programming)|inheritance]], [[Type polymorphism|polymorphism]], dynamic type allocation, and type-bound procedures, providing complete support for [[abstract data type]]s
* Data manipulation enhancements: allocatable components (incorporating TR 15581), deferred type parameters, [[volatile variable|{{code|VOLATILE}} attribute]], explicit type specification in array constructors and allocate statements, pointer enhancements, extended initialization expressions, and enhanced intrinsic procedures
* Input/output enhancements: [[Asynchronous I/O|asynchronous]] transfer, stream access, user specified transfer operations for derived types, user specified control of rounding during format conversions, named constants for preconnected units, the {{code|FLUSH}} statement, regularization of keywords, and access to error messages
* [[Function pointer|Procedure pointers]]
* Support for [[IEEE 754-2008|IEEE floating-point arithmetic]] and [[floating-point arithmetic|floating-point]] [[exception handling]] (incorporating TR 15580)
* Interoperability with the C programming language
* Support for international usage: access to [[Universal Character Set|ISO 10646]] 4-byte characters and choice of decimal or comma in numeric formatted input/output
* Enhanced integration with the host operating system: access to [[Command-line interface|command-line]] arguments, [[environment variable]]s, and processor error messages

An important supplement to Fortran 2003 was the [[International Organization for Standardization|ISO technical report]] ''TR-19767: Enhanced module facilities in Fortran.''  This report provided ''sub-modules,'' which make Fortran modules more similar to [[Modula-2]] modules.  They are similar to [[Ada (programming language)|Ada]] private child sub-units.  This allows the specification and implementation of a module to be expressed in separate program units, which improves packaging of large libraries, allows preservation of trade secrets while publishing definitive interfaces, and prevents compilation cascades.

===Fortran 2008===
ISO/IEC 1539-1:2010, informally known as Fortran 2008, was approved in September 2010.<ref>{{cite web|title=N1836, Summary of Voting/Table of Replies on ISO/IEC FDIS 1539-1, Information technology – Programming languages – Fortran – Part 1: Base language|url=https://wg5-fortran.org/N1801-N1850/N1836.pdf |archive-url=https://web.archive.org/web/20180115003040/https://wg5-fortran.org/N1801-N1850/N1836.pdf |archive-date=January 15, 2018 |url-status=live}}</ref><ref>{{cite web|title=Fortran 2008 – Last Working Draft|url=http://www.j3-fortran.org/doc/year/10/10-007.pdf |archive-url=https://web.archive.org/web/20140512222210/http://www.j3-fortran.org/doc/year/10/10-007.pdf |archive-date=May 12, 2014 |url-status=live|publisher=Gnu.Org|access-date=May 10, 2014}}</ref> As with Fortran 95, this is a minor upgrade, incorporating clarifications and corrections to Fortran 2003, as well as introducing some new capabilities.  The new capabilities include:

* Sub-modules – additional structuring facilities for modules; supersedes ISO/IEC TR 19767:2005
* [[Coarray Fortran]] – a parallel execution model
* The [[Scalable parallelism|DO CONCURRENT]] construct – for loop iterations with no interdependencies
* The CONTIGUOUS attribute – to specify storage layout restrictions
* The [[Dynamic scoping|BLOCK construct]] – can contain declarations of objects with construct scope
* [[Recursive data type|Recursive allocatable components]] – as an alternative to recursive pointers in derived types

The Final Draft international Standard (FDIS) is available as document N1830.<ref>N1830, Information technology – Programming languages – Fortran – Part 1: Base language [ftp://ftp.nag.co.uk/sc22wg5/N1801-N1850/N1830.pdf]{{dead link|date=January 2016}}</ref>

A supplement to Fortran 2008 is the [[International Organization for Standardization]] (ISO) Technical Specification (TS) 29113 on ''Further Interoperability of Fortran with C'',<ref>{{cite ISO standard |csnumber=45136 |title=ISO/IEC TS 29113:2012 – Information technology – Further interoperability of Fortran with C}}</ref><ref>{{cite web|url=https://wg5-fortran.org/N1901-N1950/N1917.pdf |archive-url=https://web.archive.org/web/20180115013236/https://wg5-fortran.org/N1901-N1950/N1917.pdf |archive-date=January 15, 2018 |url-status=live|title=Draft of the Technical Specification (TS) 29113|website=wg5-fortran.org}}</ref> which has been submitted to ISO in May 2012 for approval. The specification adds support for accessing the array descriptor from C and allows ignoring the type and rank of arguments.

===Fortran 2018===
The Fortran 2018 revision of the language was earlier referred to as Fortran 2015.<ref name="Fortran2018name">{{cite web|url=https://software.intel.com/en-us/blogs/2017/11/20/doctor-fortran-in-eighteen-is-the-new-fifteen|title=Doctor Fortran in "Eighteen is the new Fifteen"|publisher=Software.intel.com|access-date=November 20, 2017}}</ref> It was a significant revision and was released on November 28, 2018.<ref name="F2018">{{cite web|url=https://wg5-fortran.org/f2018.html|publisher=ISO|title=Fortran 2018|access-date=November 30, 2018}}</ref>

Fortran 2018 incorporates two previously published Technical Specifications:
* ISO/IEC TS 29113:2012 Further Interoperability with C<ref name="TS29113">{{cite web|url=https://wg5-fortran.org/N1901-N1950/N1942.pdf |archive-url=https://web.archive.org/web/20171201033143/https://wg5-fortran.org/N1901-N1950/N1942.pdf |archive-date=December 1, 2017 |url-status=live|title=Further Interoperability with C|publisher=ISO|access-date=November 20, 2017}}</ref>
* ISO/IEC TS 18508:2015 Additional Parallel Features in Fortran<ref name="TS18508">{{cite web|url=http://isotc.iso.org/livelink/livelink?func=ll&objId=17288706&objAction=Open|title=Additional Parallel Features in Fortran|publisher=ISO|access-date=November 20, 2017}}</ref>

Additional changes and new features include support for ISO/IEC/IEEE 60559:2011 (the version of the [[IEEE 754|IEEE floating-point standard]] before the latest minor revision IEEE {{not a typo|754–2019}}), hexadecimal input/output, IMPLICIT NONE enhancements and other changes.<ref name="F2015newfeat">{{cite web|url=http://isotc.iso.org/livelink/livelink?func=ll&objId=19044944&objAction=Open|publisher=ISO|title=The New Features of Fortran 2015|access-date=June 23, 2017}}</ref><ref name="Fortran2015Closes">{{cite web|url=https://software.intel.com/en-us/blogs/2015/09/04/doctor-fortran-in-one-door-closes|title=Doctor Fortran in "One Door Closes"|publisher=Software.intel.com|access-date=September 21, 2015}}</ref><ref name="Fortran2015">{{cite web|url=http://software.intel.com/en-us/blogs/2013/08/08/doctor-fortran-goes-dutch-fortran-2015|title=Doctor Fortran Goes Dutch: Fortran 2015|publisher=Software.intel.com|access-date=November 19, 2014
 | url-status   = dead
 | archive-url  = https://web.archive.org/web/20170401092649/software.intel.com/en-us/blogs/2013/08/08/doctor-fortran-goes-dutch-fortran-2015
 | archive-date = 2017-04-01
 | quote        = The ISO Fortran Standards Committee held its annual meeting in Delft, [...]
}}
</ref><ref>
{{cite manual |url=http://j3-fortran.org/doc/year/18/18-007r1.pdf |title=Fortran 2018 Interpretation Document |date=October 9, 2018}}
</ref>

Fortran 2018 deleted the arithmetic IF statement.  It also deleted non-block DO constructs - loops which do not end with an END DO or CONTINUE statement.  These had been an obsolescent part of the language since Fortran 90.

New obsolescences are: COMMON and EQUIVALENCE statements and the BLOCK DATA program unit, labelled DO loops, specific names for intrinsic functions, and the FORALL statement and construct.

===Fortran 2023===
Fortran 2023 (ISO/IEC 1539-1:2023) was published in November 2023, and can be purchased from the ISO.<ref>{{cite web |title=Fortran 2023 |url=https://wg5-fortran.org/f2023.html |website=wg5-fortran.org |access-date=November 30, 2023}}</ref>
Fortran 2023 is a minor extension of Fortran 2018 that focuses on correcting errors and omissions
in Fortran 2018.  It also adds some small features, including an [[enumerated type]] capability.