Dennis Ritchie - wikipedia Dennis Ritchie This is the latest accepted revision, reviewed on 11 October 2017. Dennis MacAlistair Ritchie Dennis Ritchie at the Japan Prize Foundation in May 2011 ( 1941 - 09 - 09 ) September 9, 1941 Bronxville, New York, U.S. c. October 12, 2011 ( 2011 - 10 - 12 ) ( aged 70 ) Berkeley Heights, New Jersey, U.S. Nationality American Alma mater Harvard University ( Ph. D., 1968 ) Known for ALTRAN BCPL Multics Unix Awards Turing Award ( 1983 ) National Medal of Technology ( 1998 ) IEEE Richard W. Hamming Medal ( 1990 ) Computer Pioneer Award ( 1994 ) Computer History Museum Fellow ( 1997 ) Harold Pender Award ( 2003 ) Japan Prize ( 2011 ) Scientific career Fields Computer science Institutions Lucent Technologies Bell Labs Dennis MacAlistair Ritchie ( September 9, 1941 -- c. October 12, 2011 ) was an American computer scientist. He created the C programming language and, with long - time colleague Ken Thompson, the Unix operating system. Ritchie and Thompson were awarded the Turing Award from the ACM in 1983, the Hamming Medal from the IEEE in 1990 and the National Medal of Technology from President Bill Clinton in 1999. Ritchie was the head of Lucent Technologies System Software Research Department when he retired in 2007. He was the `` R '' in K&R C, and commonly known by his username dmr. Contents 1 Personal life and career 2 C and Unix 3 Awards 4 Death 5 Legacy 6 Gallery 7 Notable work 8 See also 9 References 10 External links Personal Life and career Dennis Ritchie was born in Bronxville, New York. His father was Alistair E. Ritchie, a longtime Bell Labs scientist and co-author of The Design of Switching Circuits on switching circuit theory. As a child, Dennis moved with his family to Summit, New Jersey, where he graduated from Summit High School. He graduated from Harvard University with degrees in physics and applied mathematics. Ken Thompson ( left ) and Dennis Ritchie ( right ) Version 7 Unix for the PDP - 11, including Dennis Ritchie 's home directory : / usr / dmr In 1967, Ritchie began working at the Bell Labs Computing Sciences Research Center, and in 1968, he defended his PhD thesis on `` Program Structure and Computational Complexity '' at Harvard under the supervision of Patrick C. Fischer. However, Ritchie never officially received his PhD degree. During the 1960s, Ritchie and Ken Thompson worked on the Multics operating system at Bell Labs. However, Bell Labs pulled out of the project in 1969. Thompson then found an old PDP - 7 machine and developed his own application programs and operating system from scratch, aided by Ritchie and others. In 1970, Brian Kernighan suggested the name `` Unix '', a pun on the name `` Multics ''. To supplement assembly language with a system - level programming language, Thompson created B. Later, B was replaced by C, created by Ritchie, who continued to contribute to the development of Unix and C for many years. During the 1970s, Ritchie collaborated with James Reeds and Robert Morris on a ciphertext - only attack on the M - 209 US cipher machine that could solve messages of at least 2000 -- 2500 letters. Ritchie relates that, after discussions with the NSA, the authors decided not to publish it, as they were told that the principle was applicable to machines still in use by foreign governments. Ritchie was also involved with the development of the Plan 9 and Inferno operating systems, and the programming language Limbo. As part of an AT&T restructuring in the mid-1990s, Ritchie was transferred to Lucent Technologies, where he retired in 2007 as head of System Software Research Department.. C and Unix Ritchie is best known as the creator of the C programming language, a key developer of the Unix operating system, and co-author of the book The C Programming Language ; he was the ' R ' in K&R ( a common reference to the book 's authors Kernighan and Ritchie ). Ritchie worked together with Ken Thompson, who is credited with writing the original version of Unix ; one of Ritchie 's most important contributions to Unix was its porting to different machines and platforms. They were so influential on Research Unix that Doug McIlroy later wrote, `` The names of Ritchie and Thompson may safely be assumed to be attached to almost everything not otherwise attributed. '' Ritchie liked to emphasize that he was just one member of a group. He suggested that many of the improvements he introduced simply `` looked like a good thing to do, '' and that anyone else in the same place at the same time might have done the same thing. But Bjarne Stroustrup who designed C++ said `` If Dennis had decided to spend that decade on esoteric math, Unix would have been stillborn. '' Nowadays, the C language is widely used today in application, operating system, and embedded system development, and its influence is seen in most modern programming languages. Unix has also been influential, establishing computing concepts and principles that have been widely adopted. In an interview from 1999, Ritchie clarified that he saw Linux and BSD operating systems as a continuation of the basis of the Unix operating system, and as derivatives of Unix : I think the Linux phenomenon is quite delightful, because it draws so strongly on the basis that Unix provided. Linux seems to be among the healthiest of the direct Unix derivatives, though there are also the various BSD systems as well as the more official offerings from the workstation and mainframe manufacturers. In the same interview, he stated that he viewed both Unix and Linux as `` the continuation of ideas that were started by Ken and me and many others, many years ago. '' Awards In 1983, Ritchie and Thompson received the Turing Award for their development of generic operating systems theory and specifically for the implementation of the UNIX operating system. Ritchie 's Turing Award lecture was titled `` Reflections on Software Research ''. In 1990, both Ritchie and Thompson received the IEEE Richard W. Hamming Medal from the Institute of Electrical and Electronics Engineers ( IEEE ), `` for the origination of the UNIX operating system and the C programming language ''. In 1997, both Ritchie and Thompson were made Fellows of the Computer History Museum, `` for co-creation of the UNIX operating system, and for development of the C programming language. '' On April 21, 1999, Thompson and Ritchie jointly received the National Medal of Technology of 1998 from President Bill Clinton for co-inventing the UNIX operating system and the C programming language which, according to the citation for the medal, `` led to enormous advances in computer hardware, software, and networking systems and stimulated growth of an entire industry, thereby enhancing American leadership in the Information Age ''. In 2005, the Industrial Research Institute awarded Ritchie its Achievement Award in recognition of his contribution to science and technology, and to society generally, with his development of the Unix operating system. In 2011, Ritchie, along with Thompson, was awarded the Japan Prize for Information and Communications for his work in the development of the Unix operating system. Death Dennis Ritchie with Doug McIlroy ( left ) in May 2011 Ritchie was found dead on October 12, 2011, at the age of 70 at his home in Berkeley Heights, New Jersey, where he lived alone. First news of his death came from his former colleague, Rob Pike. The cause and exact time of death have not been disclosed. He had been in frail health for several years following treatment for prostate cancer and heart disease. Legacy Following Ritchie 's death, computer historian Paul E. Ceruzzi stated : Ritchie was under the radar. His name was not a household name at all, but... if you had a microscope and could look in a computer, you 'd see his work everywhere inside. In an interview shortly after Ritchie 's death, long time colleague Brian Kernighan said Ritchie never expected C to be so significant. Kernighan told The New York Times `` The tools that Dennis built -- and their direct descendants -- run pretty much everything today. '' Kernighan reminded readers of how important a role C and Unix had played in the development of later high - profile projects, such as the iPhone. Other testimonials to his influence followed. At his death, a commentator compared the relative importance of Steve Jobs and Ritchie, concluding that `` ( Ritchie 's ) work played a key role in spawning the technological revolution of the last forty years -- including technology on which Apple went on to build its fortune. '' Another commentator said, `` Ritchie, on the other hand, invented and co-invented two key software technologies which make up the DNA of effectively every single computer software product we use directly or even indirectly in the modern age. It sounds like a wild claim, but it really is true. '' Another said, `` many in computer science and related fields knew of Ritchie 's importance to the growth and development of, well, everything to do with computing,... '' The Fedora 16 Linux distribution, which was released about a month after he died, was dedicated to his memory. FreeBSD 9.0, released January 12, 2012 was also dedicated in his memory. Gallery Ritchie engaged in conversation in a chalet in the mountains surrounding Salt Lake City at the 1984 Usenix conference. At the same Usenix 1984 conference, Dennis Ritchie is visible in the middle, wearing a striped shirt, behind Steven Bellovin wearing a baseball hat. Notable work C ( programming language ) on which many currently used languages and technologies are based. Unix a multiuser operating system. Several workalikes ( commonly referred to as Unix - like systems ) have been developed based on Unix 's design. Some of these follow POSIX standards, again based on Unix. Unix Programmer 's Manual ( 1971 ) The C Programming Language ( book ) ( sometimes referred to as K&R ; 1978 with Brian Kernighan ) See also List of pioneers in computer science References Jump up ^ `` Archived copy ''. Archived from the original on January 3, 2015. Retrieved January 5, 2015. ^ Jump up to : Lohr, Steve ( October 12, 2011 ), `` Dennis Ritchie, Programming Trailblazer, Dies at 70 '', The New York Times, retrieved October 13, 2011, Dennis M. Ritchie, who helped shape the modern digital era by creating software tools that power things as diverse as search engines like Google and smartphones, was found dead on Wednesday at his home in Berkeley Heights, N.J. He was 70. Mr. Ritchie, who lived alone, was in frail health in recent years after treatment for prostate cancer and heart disease, said his brother Bill. ^ Jump up to : `` Unix creator Dennis Ritchie dies aged 70 ''. BBC News. October 13, 2011. Retrieved October 14, 2011. Pioneering computer scientist Dennis Ritchie has died after a long illness... The first news of Dr Ritchie 's death came via Rob Pike, a former colleague who worked with him at Bell Labs. Mr Ritchie 's passing was then confirmed in a statement from Alcatel - Lucent which now owns Bell Labs. ^ Jump up to : Rob Pike ( October 12, 2011 ), ( untitled post to Google+ ), retrieved October 14, 2011, I just heard that, after a long illness, Dennis Ritchie ( dmr ) died at home this weekend. I have no more information. Jump up ^ Campbell - Kelly, Martin ( October 13, 2011 ), `` Dennis Ritchie obituary '', The Guardian, retrieved October 13, 2011, Dennis MacAlistair Ritchie, computer scientist, born 9 September 1941 ; died 12 October 2011 Jump up ^ Liz, Keill ( February 1, 2011 ). `` Berkeley Heights man wins Japan Prize for inventing UNIX operating system ''. Independent Press. Retrieved October 17, 2011. Ritchie, 69, has lived in Berkeley Heights for 15 years. He was born in Bronxville, New York, grew up in Summit and attended Summit High School before going to Harvard University. Jump up ^ van Renesse, Robbert ( January 2014 ). `` The First SIGOPS Dennis M. Ritchie Doctoral Dissertation Award ''. ACM SIGOPS Operating Systems Review. 48 ( 1 ) : 100. doi : 10.1145 / 2626401.2626421. Jump up ^ Ritchie, Dennis M. `` The Evolution of the Unix Time - sharing System ''. Retrieved October 31, 2016. Jump up ^ Ritchie, Dennis. `` The Development of the C Language ''. Bell Labs. Retrieved October 31, 2016. ^ Jump up to : `` Dabbling in Cryptography ''. Bell-labs.com. May 5, 2000. Retrieved November 14, 2016. Jump up ^ `` Dennis Ritchie, father of C programming language, dies ''. cnet. October 13, 2011. Jump up ^ ( Pioneer Programmer Shaped the Evolution of Computers, Wall Street Journal, October 14, 2011, p. A7 ) Jump up ^ McIlroy, M.D. ( 1987 ). A Research Unix reader : annotated excerpts from the Programmer 's Manual, 1971 -- 1986 ( PDF ) ( Technical report ). CSTR. Bell Labs. 139. Jump up ^ `` Unix 's founding fathers ''. The Economist. June 10, 2004. Retrieved January 16, 2017. ^ Jump up to : Benet, Manuel ( 1999 ). `` Interview With Dennis M. Ritchie ''. LinuxFocus.org. Jump up ^ Ritchie, Dennis M. ( 1987 ), `` 1983 Turing Award Lecture : Reflections on Software Research '', ACM Turing Award Lectures : The First Twenty Years 1666 -- 1985, ACM Press Anthology Series, Addison - Wesley Publishing Company, pp. 163 -- 169, retrieved January 30, 2012 Jump up ^ `` IEEE Richard W. Hamming Medal Recipients '' ( PDF ). IEEE. Retrieved May 29, 2011. Jump up ^ CHM. `` Dennis Ritchie -- CHM Fellow Award Winner ''. Retrieved March 30, 2015. Jump up ^ `` Archived copy ''. Archived from the original on March 27, 2006. Retrieved September 6, 2006. Jump up ^ `` Archived copy ''. Archived from the original on October 11, 2003. Retrieved November 4, 2003. Jump up ^ `` Dennis Ritchie, Bell Labs Researcher and Co-Inventor of Unix, Receives 2005 Industrial Research Institute Achievement Award ''. Alcatel - Lucent Press Release. November 15, 2005. Retrieved February 8, 2012. Jump up ^ Benny, Evangelista ( January 25, 2011 ). `` Ken Thompson, Dennis Ritchie win Japan Prize ''. San Francisco Chronicle. Jump up ^ Associated Press ( October 13, 2011 ), `` Summary Box : Dennis Ritchie, pioneer in computer programming at Bell Labs, dies at 70 '', The Washington Post, retrieved October 14, 2011, NOT KNOWN : Alcatel - Lucent confirmed his death to The Associated Press but would not disclose the cause of death or when Ritchie died. Jump up ^ Gallagher, Sean ( October 13, 2011 ). `` Dennis Ritchie, Father of C and Co-Developer of Unix, Dies ''. Wired. Retrieved October 13, 2011. Jump up ^ Binstock, Andrew. `` Dennis Ritchie, in Memoriam ''. Dr. Dobb 's Journal. Dr. Dobb 's Journal. Retrieved October 14, 2011. Jump up ^ Langer, Emily ( October 14, 2011 ). `` Dennis Ritchie, founder of Unix and C, dies at 70 ''. Washington Post. Retrieved November 3, 2011. Jump up ^ Shishir Prasad ( November 4, 2011 ). `` No one thought ' C ' would become so big : Brian Kernighan ''. Forbes India. Retrieved November 28, 2011. Q Did Dennis Ritchie or you ever think C would become so popular ? ( Kernighan ) I do n't think that at the time Dennis worked on Unix and C anyone thought these would become as big as they did. Unix, at that time, was a research project inside Bell Labs. Jump up ^ Steve Lohroct ( October 13, 2011 ). `` Dennis Ritchie, 70, Dies, Programming Trailblazer ''. The New York Times. Retrieved November 14, 2016. Jump up ^ `` Myths of Steve Jobs ''. Deccan Herald. November 28, 2011. Retrieved November 28, 2011. Dennis Ritchie, the inventor of the C language and co-inventor of the Unix operating system, died a few days after Steve Jobs. He was far more influential than Jobs. Jump up ^ Subhajit Datta ( November 14, 2011 ). `` The tale of three deeply different technologists ''. The Hindu. Retrieved November 28, 2011. Jump up ^ David Cardinal ( November 2, 2011 ). `` Dennis Ritchie, creator of C, bids `` goodbye, world '' ``. Extreme Tech. Retrieved November 28, 2011. The book came off the shelf in service of teaching another generation a simple, elegant way to program that allows the developer to be directly in touch with the innards of the computer. The lowly integer variable -- int -- has grown in size over the years as computers have grown, but the C language and its sparse, clean, coding style live on. For that we all owe a lot to Dennis Ritchie. Jump up ^ `` Dennis Ritchie and John McCarthy : Dennis Ritchie and John McCarthy, machine whisperers, died on October 8th and 24th respectively, aged 70 and 84 ''. The Economist. November 5, 2011. Retrieved November 28, 2011. NOW that digital devices are fashion items, it is easy to forget what really accounts for their near - magical properties. Without the operating systems which tell their different physical bits what to do, and without the languages in which these commands are couched, the latest iSomething would be a pretty but empty receptacle. The gizmos of the digital age owe a part of their numeric souls to Dennis Ritchie and John McCarthy. Jump up ^ `` The Strange Birth and Long Life of Unix ''. Newswise. November 23, 2011. Retrieved November 28, 2011. Four decades ago, Ken Thompson, the late Dennis Ritchie, and others at AT&T 's Bell Laboratories developed Unix, which turned out to be one of the most influential pieces of software ever written. Their work on this operating system had to be done on the sly, though, because their employer had recently backed away from operating - systems research. Jump up ^ Shyamanuja Das ( November 1, 2011 ). `` The forgotten tech luminaries : The new generation of the digital age owe a part of their numeric souls to Dennis Ritchie and John McCarthy ''. Ciol.com. Archived from the original on January 28, 2012. Retrieved November 28, 2011. UNIX, to the development of which Ritchie greatly contributed, and whose C made it possible it to be ported to other machines, is, even today, in its different avatars, the de facto OS for anything that is mission critical. Solaris, AIX, HP - UX, Linux -- all these are derived from UNIX. Jump up ^ Duncan, Geoff ( October 13, 2011 ). `` Was Dennis Ritchie more important than Steve Jobs ? ''. Digital Trends. Retrieved November 14, 2016. Jump up ^ Perlow, Jason ( October 9, 2015 ). `` Without Dennis Ritchie, there would be no Steve Jobs ''. ZDNet.com. Retrieved November 14, 2016. Jump up ^ `` What Can We Learn From Dennis Ritchie ? ''. TechCrunch.com. October 15, 2011. Retrieved November 14, 2016. Jump up ^ Phoronix. `` Red Hat Releases Fedora 16 `` Verne '' ``. Retrieved November 8, 2011. Jump up ^ The FreeBSD project. `` FreeBSD - 9.0 Announcement ''. Retrieved January 12, 2012. External links Wikimedia Commons has media related to Dennis Ritchie. Wikiquote has quotations related to : Dennis Ritchie Listen to this article ( info / dl ) This audio file was created from a revision of the article `` Dennis Ritchie '' dated June 17, 2006, and does not reflect subsequent edits to the article. ( Audio help ) More spoken articles Dennis Ritchie 's home page at Bell Labs `` The C Family of Languages : Interview with Dennis Ritchie, Bjarne Stroustrup, and James Gosling '' -- article in Java Report, 5 ( 7 ), July 2000 and C++ Report, 12 ( 7 ), July / August 2000 `` The Guru '' -- article in Linux Magazine, June 2001 Dennis Ritchie 's video interview June 2011 Works by or about Dennis Ritchie in libraries ( WorldCat catalog ) Dennis Ritchie at Find a Grave Dennis Ritchie at DMOZ IEEE Richard W. Hamming Medal 1988 -- 2000 Richard Hamming ( 1988 ) Irving S. Reed ( 1989 ) Dennis Ritchie / Ken Thompson ( 1990 ) Elwyn Berlekamp ( 1991 ) Lotfi A. Zadeh ( 1992 ) Jorma Rissanen ( 1993 ) Gottfried Ungerboeck ( 1994 ) Jacob Ziv ( 1995 ) Mark Semenovich Pinsker ( 1996 ) Thomas M. Cover ( 1997 ) David D. Clark ( 1998 ) David A. Huffman ( 1999 ) Solomon W. Golomb ( 2000 ) 2001 -- present Alexander G. Fraser ( 2001 ) Peter Elias ( 2002 ) Claude Berrou / Alain Glavieux ( 2003 ) Jack K. Wolf ( 2004 ) Neil Sloane ( 2005 ) Vladimir Levenshtein ( 2006 ) Abraham Lempel ( 2007 ) Sergio Verdú ( 2008 ) Peter Franaszek ( 2009 ) Whitfield Diffie / Martin Hellman / Ralph Merkle ( 2010 ) Toby Berger ( 2011 ) Michael Luby / Amin Shokrollahi ( 2012 ) Robert Calderbank ( 2013 ) Thomas Richardson / Rüdiger Urbanke ( 2014 ) Imre Csiszár ( 2015 ) Abbas El Gamal ( 2016 ) Shlomo Shamai ( 2017 ) A.M. Turing Award laureates Alan Perlis ( 1966 ) Maurice Vincent Wilkes ( 1967 ) Richard Hamming ( 1968 ) Marvin Minsky ( 1969 ) James H. Wilkinson ( 1970 ) John McCarthy ( 1971 ) Edsger W. Dijkstra ( 1972 ) Charles Bachman ( 1973 ) Donald Knuth ( 1974 ) Allen Newell / Herbert A. Simon ( 1975 ) Michael O. Rabin / Dana Scott ( 1976 ) John Backus ( 1977 ) Robert W. Floyd ( 1978 ) Kenneth E. Iverson ( 1979 ) Tony Hoare ( 1980 ) Edgar F. Codd ( 1981 ) Stephen Cook ( 1982 ) Ken Thompson / Dennis Ritchie ( 1983 ) Niklaus Wirth ( 1984 ) Richard Karp ( 1985 ) John Hopcroft / Robert Tarjan ( 1986 ) John Cocke ( 1987 ) Ivan Sutherland ( 1988 ) William Kahan ( 1989 ) Fernando J. Corbató ( 1990 ) Robin Milner ( 1991 ) Butler Lampson ( 1992 ) Juris Hartmanis / Richard E. Stearns ( 1993 ) Edward Feigenbaum / Raj Reddy ( 1994 ) Manuel Blum ( 1995 ) Amir Pnueli ( 1996 ) Douglas Engelbart ( 1997 ) Jim Gray ( 1998 ) Fred Brooks ( 1999 ) Andrew Yao ( 2000 ) Ole - Johan Dahl / Kristen Nygaard ( 2001 ) Ron Rivest / Adi Shamir / Leonard Adleman ( 2002 ) Alan Kay ( 2003 ) Vint Cerf / Bob Kahn ( 2004 ) Peter Naur ( 2005 ) Frances E. Allen ( 2006 ) Edmund M. Clarke / E. Allen Emerson / Joseph Sifakis ( 2007 ) Barbara Liskov ( 2008 ) Charles P. Thacker ( 2009 ) Leslie G. Valiant ( 2010 ) Judea Pearl ( 2011 ) Shafi Goldwasser / Silvio Micali ( 2012 ) Leslie Lamport ( 2013 ) Michael Stonebraker ( 2014 ) Martin Hellman / Whitfield Diffie ( 2015 ) Tim Berners - Lee ( 2016 ) VIAF : 616522 LCCN : n77018721 ISNI : 0000 0000 8080 3719 GND : 110760239 SUDOC : 059254661 BNF : cb126571234 ( data ) MGP : 155881 NDL : 00454287 NKC : xx0041904 IATH : w6j133qx DBLP : r / DennisRitchie ACM DL : 81100458439 Retrieved from `` https://en.wikipedia.org/w/index.php?title=Dennis_Ritchie&oldid=804809839 '' Categories : 1941 births 2011 deaths American computer scientists American technology writers Harvard University alumni Turing Award laureates Unix people Plan 9 people Inferno ( operating system ) people C ( programming language ) Scientists at Bell Labs National Medal of Technology recipients Programming language designers People from Bronxville, New York People from Berkeley Heights, New Jersey People from Summit, New Jersey Innovators Hidden categories : Wikipedia pending changes protected pages ( level 1 ) Use mdy dates from September 2017 Articles with hCards Spoken articles Articles with hAudio microformats Find a Grave template with ID same as Wikidata Articles with DMOZ links Wikipedia articles with VIAF identifiers Wikipedia articles with LCCN identifiers Wikipedia articles with ISNI identifiers Wikipedia articles with GND identifiers Wikipedia articles with BNF identifiers Wikipedia articles with SNAC - ID identifiers Wikipedia articles with DBLP identifiers Wikipedia articles with ACM - DL identifiers Talk Contents About Wikipedia Wikiquote Alemannisch Asturianu Azərbaycanca تۆرکجه বাংলা Bân - lâm - gú Беларуская Беларуская ( тарашкевіца ) ‎ Български Bosanski Català Čeština Cymraeg Dansk Deutsch Eesti Ελληνικά Español Esperanto Euskara فارسی Français Gaeilge Gàidhlig Galego 한국어 Հայերեն हिन्दी Hrvatski Bahasa Indonesia Íslenska Italiano עברית ಕನ್ನಡ Қазақша Kurdî Latviešu Lumbaart Magyar Македонски Malagasy മലയാളം मराठी Nederlands नेपाल भाषा 日本 語 Norsk Occitan ਪੰਜਾਬੀ Polski Português Română Русский संस्कृतम् Scots Shqip Simple English Slovenčina Slovenščina کوردی Српски / srpski Srpskohrvatski / српскохрватски Suomi Svenska Tagalog தமிழ் తెలుగు ไทย Türkçe Українська Tiếng Việt Winaray 中文 Edit links This page was last edited on 11 October 2017, at 08 : 41. Text is available under the Creative Commons Attribution - ShareAlike License ; additional terms may apply. By using this site, you agree to the Terms of Use and Privacy Policy. Wikipedia ® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization. About Wikipedia

Question: who is called as father of c programming language
Answer: Dennis MacAlistair Ritchie