View source for Watcom C/C++

{{Short description|Commercial product for developing code}}
{{Infobox software
| name                       = Open Watcom C/C++
| logo                       = Watcom logo.png
| screenshot                 = 
| caption                    = 
| collapsible                = 
| author                     = [[Watcom]]
| developer                  = [[Sybase]], [[SciTech Software]]
| released                   = {{Start date and age|1988|br=yes}}
| latest release version     = 2.0 (continuous updates)
| latest release date        = {{Start date and age|2024|12|04|br=yes}}<ref>{{Cite web |title=Current-build<!  Releases · open-watcom/open-watcom-v2 --> |url=https://github.com/open-watcom/open-watcom-v2/releases |access-date=2024-12-09 |website=GitHub |language=en}}</ref>
| repo                       = {{URL|https://github.com/open-watcom/open-watcom-v2}}
| programming language       = [[C (programming language)|C]], [[C++]]
| operating system           = [[DOS]], [[Microsoft Windows|Windows]], [[OS/2]], [[Linux]]
| size                       = 66–84 MB
| platform                   = [[x86]], [[IA-32]], [[x86-64]]
| language                   = 
| genre                      = [[Integrated development environment]]
| license                    = [[Sybase Open Watcom Public License]] version 1.0
| website                    = {{URL|openwatcom.org}} , {{URL|https://github.com/open-watcom/open-watcom-v2}}
}}

'''Watcom C/C++''' (currently '''Open Watcom C/C++''') is an [[integrated development environment]] (IDE) product from [[Watcom International Corporation]] for the [[C (programming language)|C]], [[C++]], and [[Fortran]] [[programming language]]s.  Watcom C/C++ was a commercial product until it was discontinued, then released under the [[Sybase Open Watcom Public License]] as Open Watcom C/C++.  It features tools for [[Software development|developing]] and [[debugging]] code for [[DOS]], [[OS/2]], [[Microsoft Windows|Windows]], and [[Linux]] [[operating systems]], which are based upon 16-bit [[x86]], 32-bit [[IA-32]], or 64-bit [[x86-64]] compatible processors.

==History==
In 2000, [[Sybase]], who owned Watcom International Corporation halted the commercial sale of the Watcom C/C++ and [[Fortran]] compilers. In 2003, SciTech Software Inc, a customer of Sybase, negotiated wth Sybase, to have the code for the compilers released as an open source project under a new name, Open Watcom.<ref>{{cite web |url=http://www.openwatcom.com/about.php |archive-date=April 29, 2016 |archive-url=https://web.archive.org/web/20160429054902/http://www.openwatcom.com/about.php |title=Open Watcom dot org About us |publisher=OpenWatcom.org wiki |url-status=dead}}</ref> The Watcom C/C++ compiler and the Watcom Fortran compiler were made available free of charge as the ''Open Watcom'' package.

The last stable version endorsed by the original openwatcom.org team was 1.9, released in June 2010.<ref>{{cite web |url=https://www.openwatcom.org/index.php/Main_Page |archive-date=January 18, 2015 |archive-url=https://web.archive.org/web/20150118220613/http://www.openwatcom.org/index.php/Main_Page |title=Latest Release (June 2010) - Open Watcom |publisher=OpenWatcom.org wiki |url-status=dead}}</ref><ref name="OWRC">{{cite web |title=C Compiler Release Changes |url=https://www.openwatcom.org/index.php/C_Compilers_Release_Changes |website=Open Watcom |archive-url=https://web.archive.org/web/20150203100434/http://www.openwatcom.org/index.php/C_Compilers_Release_Changes |archive-date=February 3, 2015 |date=March 9, 2010 |url-status=dead}}</ref>

A community-based [[software fork|forked]] version 2.0 (with continuous updates under the same version moniker) was released after the original codebase was seemingly no longer developed by the original team. It includes miscellaneous bugfixes, supports 64-bit hosts (Windows and Linux), built-in text editor, 2-phase build system, and has a DOS version that supports [[long filename]]s (LFN).<ref name="release20150402">[https://open-watcom.github.io Open Watcom v2 Fork]</ref>

===Release history===
The ''Open Watcom Wiki'' has a comprehensive history.<ref name="hist"/><ref name="OWRC"/>

{{Hidden begin
|titlestyle = background: #ccccff; font-size: 100%; width: 100%;
|header     = Release history table
}}
{| class="wikitable"
! Date || Product || Notes
|-
| 1984 || {{Nowrap|Waterloo C for [[S/370]]}} ||
|-
| 1985 || {{sp}} ||
* Work on current code generator codebase started
|-
| 1988 || {{Nowrap|Watcom C 6.0}} ||
* DOS host and target only
* Included a debugger and full set of [[runtime library|runtime libraries]]
* Generated better code than other compilers at the time
* Watcom C Version 6.5 contained Graphics Library similar to Microsoft Graphics Library
* Real mode support only{{cn|date=August 2023}}
|-
| 1989 || {{Nowrap|Watcom C 7.0}} ||
|-
| 1989 || {{Nowrap|Watcom C 7.0/386}} ||
* First 32-bit version, DOS host and target only
* Supported [[Phar Lap (company)|Phar Lap]] [[DOS extender]]
* Did not come with a [[Linker (computing)|linker]] or debugger
|-
| 1990 || {{Nowrap|Watcom C 8.0}} ||
|-
| 1990 || {{Nowrap|Watcom C 8.0/386}} ||
* Added [[Linker (computing)|linker]], librarian, [[debugger]], and [[profiling (computer programming)|profiler]]
|-
| 1991 || {{Nowrap|Watcom C 8.5}} ||
|-
| 1991 || {{Nowrap|Watcom C 8.5/386}} ||
* Shipped with [[DOS/4GW]]
* [[Windows 3.0]] supported (Win386 extender)
* [[Unicode]] support
* [[OS/2]] hosted executables added
|-
| 1992 || {{Nowrap|Watcom C 9.0}} ||
|-
| 1992 || {{Nowrap|Watcom C 9.0/386}} ||
* OS/2 2.0 host and target support
* [[Intel 80486|486]] optimizations
* Based pointer support
|-
| {{sp}} || {{Nowrap|Watcom C 9.01/386}} ||
* [[Windows 3.1]] support
|-
| 1993 || {{Nowrap|Watcom C/C++ 9.5}} ||
|-
| 1993 || {{Nowrap|Watcom C/C++ 9.5/386}} ||
* C++ compiler added
* [[Intel P5 (microarchitecture)|Pentium]] optimizations
* [[Windows NT]] host and target support
|-
| 1994 || {{Nowrap|Watcom C/C++ 10.0}} ||
* [[Microsoft Foundation Class Library|MFC]] included
* [[Precompiled header]] support
* 16-bit and 32-bit tools merged into single package
* Redesigned debugger
* C++ [[class browser]] added
* Windows [[resource editor]]s added
* Graphical [[Integrated development environment|IDE]] for Windows and OS/2
|-
| 1995 || {{Nowrap|Watcom C/C++ 10.5}} ||
* Native C++ exception handling on OS/2 and [[Win32]]
* [[Windows 95]] and [[Windows NT 3.5|NT 3.5]] support
* [[TCP/IP]] remote debugging
|-
| 1996 || {{Nowrap|Watcom C/C++ 10.6}} ||
* [[Structured exception handling]] in C
* Improved compatibility with [[Microsoft]] compilers
|-
| 1997 Q1<ref>[https://web.archive.org/web/20001005050645/http://dynamic.sybase.com/press_releases/press_releases/ExternalItem/0,1099,6,00.html SYBASE INC. ANNOUNCES WATCOM C/C++ VERSION 11.0 Includes New Support For MMX Technology and Improved C++ language Support]</ref> || {{Nowrap|Watcom C/C++ 11.0}} ||
* ''[[Namespace]]'', [[RTTI]], and new style [[type conversion|cast]] support in C++ compiler
* 64-bit integer support
* Multi-byte character support in libraries
* Incremental linking support
* [[COFF]] and [[Executable and Linkable Format|ELF]] [[object file]] support in linker and librarian
* Microsoft clone tools added
* [[Dynamic-link library|DLL]] based tools for better IDE integration
* MMX support, including debugging
* Pentium Pro optimizations, including branch prediction
* [[Novell NLM]] support
|-
| 1998 || {{Nowrap|Watcom C/C++ 11.0B}} ||
|-
| 1999-06-30 || {{sp}} ||
* Sybase issues [[end-of-life (product)|end-of-life]] notice for Watcom C/C++ 11.0<ref>[https://web.archive.org/web/20001205233700/http://techinfo.sybase.com/css/techinfo.nsf/DocId/ID=20510 End of Life Notice for Watcom C/C++ Version 11.0]</ref>
|-
| 2000-08-22 || {{sp}} ||
* Sybase announces open sourcing of Watcom tools<ref>[https://web.archive.org/web/20000925164208/http://www.sybase.com/detail/1,3151,1010040,00.html Sybase to Open Source Watcom C/C++ and Fortran Compilers - SciTech Software Selected as Official Maintainer for the Open Watcom Project]</ref>
|-
| 2001-09-27 || {{Nowrap|Watcom C/C++ 11.0c Beta}} ||
|-
| 2002-12-21 || {{Nowrap|Watcom C/C++ 11.0c}} ||
|-
| 2003-01-28 || {{Nowrap|Open Watcom 1.0}} ||
|-
| 2003-08-12 || {{Nowrap|Open Watcom 1.1}} ||
|-
| 2004-01-07 || {{Nowrap|Open Watcom 1.2}} ||
|-
| 2004-08-03 || {{Nowrap|Open Watcom 1.3}} ||
|-
| 2005-12-14 || {{Nowrap|Open Watcom 1.4}} ||
|-
| 2006-04-26 || {{Nowrap|Open Watcom 1.5}} ||
|-
| 2006-12-15 || {{Nowrap|Open Watcom 1.6}} ||
|-
| 2007-08-18 || {{Nowrap|Open Watcom 1.7}} ||
|-
| 2007-10-23 || {{Nowrap|Open Watcom 1.7a}} ||
|-
| 2009-02-21 || {{Nowrap|Open Watcom 1.8}} ||
|-
| 2010-06-02 || {{Nowrap|Open Watcom 1.9}} ||
* '''Last version released via https://www.openwatcom.org/'''
|-
| initial release: 2015-04-02<br/>continuous updates later on, up until at least 2025 || {{Nowrap|Open Watcom 2.0 Beta}} || 
* GitHub V2 fork, numerous fixes<ref name="release20150402"/>
* Open Watcom ported to 64-bit hosts (Windows and Linux)
* Resource compiler and Resource editor support WIN64 executables
* built-in text editor
* two-phase build system
* DOS version of tools support [[long filename]]s (LFN)
|}
{{Hidden end}}

==License==
{{Main|Sybase Open Watcom Public License}}
The [[Open Source Initiative]] has approved the license as [[open-source license|open source]], but [[Debian]], [[Fedora (operating system)|Fedora]] and the [[Free Software Foundation]] have rejected it because "It requires you to publish the source code publicly whenever you “Deploy” the covered software, and “Deploy” is defined to include many kinds of private use."<ref>{{cite web|last1=Free Software Foundation|title=Various Licenses and Comments about Them|url=https://www.gnu.org/licenses/license-list.html#Watcom|website=GNU Operating System|access-date=Dec 23, 2014}}</ref>

==Design==
The compiler can be operated from, and generate executable code for, the [[DOS]], [[OS/2]], [[Microsoft Windows|Windows]], Linux [[operating systems]]. It also supports [[NetWare Loadable Module|NLM]] targets for [[Novell NetWare]]. There is ongoing work to extend the targeting to [[Linux]]<ref>[https://web.archive.org/web/20150506003855/http://openwatcom.org/index.php/Installing_Open_Watcom_on_Linux Installing Open Watcom on Linux - Open Watcom]. OpenWatcom.org wiki.</ref> and modern [[BSD]] (e.g., [[FreeBSD]]) operating systems, running on [[x86]], [[PowerPC]], and other processors.

The code is portable and, like many other open source compiler projects such as [[GNU Compiler Collection|GCC]] or [[LCC (compiler)|LCC]] the compiler backend (code generator) is retargetable.

==Uses==
In the mid-1990s some of the most technically ambitious [[DOS]] [[computer game]]s such as ''[[Doom (1993 video game)|Doom]]'',<ref name="hist">[https://web.archive.org/web/20210324032810/http://wiki.openwatcom.org/index.php/History History - Open Watcom]. OpenWatcom.com wiki.</ref> ''[[Descent (video game)|Descent]]'',<ref name="hist" /> ''[[Duke Nukem 3D]]'',<ref name="hist" /> ''[[Rise of the Triad]]'',<ref name="rott">{{cite web|url=http://legacy.3drealms.com/faq/rottfaq30.txt|title=RotT was written in Watcom C++ v10.0 with the Rational Systems DOS/4GW extender}}</ref> and [[Tomb Raider (1996 video game)|Tomb Raider]] were built using Watcom C/C++ using the [[DOS/4GW]] [[protected mode]] extender with the Watcom compiler.

It was used to port the game [[Retro City Rampage]] to DOS in 2015.<ref>{{ cite web | url = https://www.gamedeveloper.com/programming/how-5-years-of-burning-ambition-brought-i-retro-city-rampage-i-to-dos |title=How 5 years of burning ambition brought Retro City Rampage to DOS |date=10 July 2015 |publisher=Gamasutra }}</ref>

It was used by [[VirtualBox]] to compile the [[BIOS]].<ref>{{Cite web|url=https://www.virtualbox.org/ticket/12011|title=#12011 (Compiling BIOS requires Open Watcom compiler)– Oracle VM VirtualBox|website=www.virtualbox.org|access-date=2017-06-17}}</ref>

Current development for [[FreeDOS]] requires that all C [[source code]] must be compilable by Open Watcom C.<ref>{{cite web |title=FreeDOS Spec |url=http://wiki.freedos.org/wiki/index.php/FreeDOS_Spec |publisher=[[FreeDOS]] |archive-url=https://web.archive.org/web/20190501051417/http://wiki.freedos.org/wiki/index.php/FreeDOS_Spec |archive-date=May 1, 2019 |url-status=live}}</ref>

Open Watcom is the recommended compiler for application and driver development for the OS/2-based [[ArcaOS]] operating system.<ref>{{cite web|url=https://www.arcanoae.com/wiki/information-for-developers/|title=Information for developers|website=arcanoae.com|access-date=2020-09-06}}</ref>

==Compatibility==
Open Watcom's syntax supports many conventions{{Which|date=October 2018}} introduced by other compilers, such as [[Microsoft]]'s and [[Borland Software Corporation|Borland]]'s, including differing conventions{{Which|date=October 2018}} regarding (for instance) the number of leading underscores on the "asm" tag. Code written specifically for another compiler rather than standard-compliant C or C++ will often compile with the Watcom compiler.

The compiler supports C89/C90 standards by default.

Open Watcom supports partial compatibility with the [[C99]] standard. It implements the most commonly used parts of the standard. However, they are enabled only through the undocumented command-line switch "-za99". Three C99 features have been bundled as [[ANSI C#C90|C90]] Extension since pre-v1.0: C++ style comments (//), flexible array members, trailing comma allowed in enum declaration.<ref>{{cite web|url=https://wiki.openwatcom.org/index.php/C99_Compliance |title=C99 compliance in Open Watcom |archive-url=https://web.archive.org/web/20210329095056/http://wiki.openwatcom.org/index.php/C99_Compliance |archive-date=2021-03-29}}</ref>

The compiler currently doesn't support any new{{When|date=October 2018}} major [[C11 (C standard revision)|C11]] features, though the C library does include "Safe C" functions. It is specified in ISO/IEC TR 24731-1<ref>[https://www.open-std.org/jtc1/sc22/wg14/www/docs/n1225.pdf ISO/IEC TR 24731-1; Extension to the C Library, Part 1: Bounds-checking interfaces.]</ref><ref name="N1969">[https://www.open-std.org/jtc1/sc22/wg14/www/docs/n1969.htm WG14 N1969 — "Updated Field Experience With Annex K — Bounds Checking Interfaces", Carlos O'Donell, Martin Sebor]</ref> and known as "Bounds-checking interfaces (Annex K)" in C11. Some function name examples are strcpy_s(), memcpy_s(), printf_s().<ref>{{cite web|url=http://wiki.openwatcom.org/index.php/Safer_C_Library |title=Open Watcom Safer C Library |access-date=2020-11-30}}</ref>  This library was released along with Open Watcom 1.5 in April 2006.

==Reception==
In a February 1989 overview of optimizing C compilers, ''[[BYTE (magazine)|BYTE]]'' praised Watcom C 6.5's "unmatched execution speed" and noted that it was the most [[ANSI C]]-compliant. The magazine advised, "If speed is absolutely critical and [[OS/2]] compatibility isn't, choose Watcom".<ref name="byte198902">{{Cite magazine |last1=Apiki |first1=Steven |last2=Udell |first2=Jon |date=February 1989 |title=Smoothing Out C |url=https://archive.org/details/eu_BYTE-1989-02_OCR/page/n225/mode/1up?view=theater |access-date=2024-10-08 |magazine=BYTE |pages=170–186}}</ref>

==See also==
* [[Open Watcom Assembler]]

==References==
{{Reflist}}

==Further reading==
* [https://web.archive.org/web/19970712221411/http://www.byte.com/art/9410/sec12/art5.htm Watcom C/C++ Gets a New Face] – review in October 1994 BYTE magazine
* [https://web.archive.org/web/20220304045500/http://www.azillionmonkeys.com/qed/watfaq.shtml The WATCOM C/C++ Programmer's FAQ]

==External links==
;Current
* [https://github.com/open-watcom/open-watcom-v2 Open Watcom 2.0 fork] – GitHub

;Archives
* [https://github.com/open-watcom/open-watcom-1.9 Open Watcom 1.9] – GitHub
* {{Official website|openwatcom.org|Open Watcom}} 1.9 – ({{webarchive |url=https://web.archive.org/web/20150317091931/http://www.openwatcom.org/index.php/Main_Page |date=March 17, 2015 }})
* Sybase Watcom C/C++ version 11.0 – ({{webarchive |url=https://web.archive.org/web/19991013131936/http://sybase.com/products/languages/watccpl.html |date=October 13, 1999 }})

{{Integrated development environments}}
{{CProLang}}

[[Category:C (programming language) compilers]]
[[Category:C++ compilers]]
[[Category:Formerly proprietary software]]
[[Category:2003 software]]