13 Feb 2024

Dennis Ritchie, who lived between September 9, 1941 and October 12, 2011, is known for his contributions to the C programming language, the B programming language and the Unix operating system, as well as his contributions to the ALTRAN programming language, the BCPL and the Multics operating system during his 70 years of life.

Education Life

Born on September 9, 1941 in New York, USA, Ritchie graduated from Summit High School in New Jersey, the alma mater of SAS Institute founder Anthony James Barr, before graduating from Harvard University in 1963 with a degree in physics. After graduation, he continued his studies in applied mathematics at Harvard University.
Although many sources state that Ritchie received his PhD in 1968 for his thesis "Program Structure and Computational Complexity", Ritchie's family stated that Dennis Ritchie did not qualify for the doctorate when preparing the application file for an award to be organized in his name after Ritchie's death. Since Ritchie was a man who did not share much of his private life, even those closest to him learned about this later.

Work Life

In 1967, like his father Alistair E. Ritchie, Dennis Ritchie started his career at Bell Laboratories. He worked with Ken Thompson on his first project at Bell Laboratories, the Multics operating system. During the Multics operating system studies, Ken Thompson developed an operating system from scratch and Dennis Ritchie helped him. This operating system was named Unix in 1970 by its namesake, Brian Kernighan.

In the 1970s, Ritchie also worked on the M-209, a mechanical encryption machine used during World War II. Although the results of these studies were successful, they were not published by the government due to concerns that they might also work on existing devices.
During his time at AT&T, Dennis Ritchie also worked on the operating systems Plan 9 and Inferno and the Limbo programming language.

In the mid-1990s, he transferred to Lucent Technologies as Head of Systems Software Research, a position he held until his retirement in 2007.


Unix is an operating system that supports multitasking and multiple users. The most widely used operating systems today, MacOS and Linux, are Unix-like operating systems.

The Unix operating system was started as a hobby project by Ken Thompson. In an interview, Thompson stated that he enjoyed playing games and that he started developing Unix to serve this purpose. Although the original version of Unix was written in Assembly programming language, Thompson and Ritchie needed a higher level programming language, so they started developing the B programming language derived from BCPL.

Since BCPL was a non-data-type programming language and B was derived from BCPL, B was a non-data-type programming language. Over time, the lack of data types in the B programming language became a disadvantage in the development of Unix system software. Dennis Ritchie, who developed most of the system software, started to transform the B programming language into the C programming language, inspired by Assembly.

After the development of the C programming language, the Unix operating system became an operating system developed with Assembly and C programming languages.

C Programming Language

The C programming language is a structured programming language derived from the B programming language. It was developed in 1972 by Dennis Ritchie to facilitate the development of Unix system applications.

Although today C is considered a low-level programming language, in the 1970s C was considered a high-level programming language.

C programming language is the most widely used programming language as of May 2020. Windows, Linux, Unix and many other operating systems are developed with C programming language.

C programming language has inspired many programming languages after becoming popular with the book "C Programming Language". The main programming languages that we can see the traces of the C programming language:

  • C++
  • Java
  • C#
  • Perl
  • PHP
  • JavaScript
  • ASP
  • Objective-C
  • Go
  • Python


  • C Programming Language (1978 - K&R with Brian Kernighan)
  • The Unix Programmer's Handbook (1971)

Unix Programmer's Guide

Dennis Ritchie, together with his longtime friend and colleague Ken Thompson, published the Unix Programmer's Guide in 1971. As the title suggests, this book is a guide for people who want to program in the Unix operating system. The second edition of the book was published in 1972.

Programming Language (K&R)

Later, Dennis Ritchie published the first edition of the book "C Programming Language" with Brian Kernighan in 1978 as a user manual of the programming language he developed. The second edition of the book was published in 1988, 10 years after the first edition. The popularity of the C programming language increased rapidly with the publication of this book.
Due to the similarity of the name of the book with the programming language, the book is often referred to as K&R. K&R comes from the initials of the surnames of the authors of the book.

Although there are many books written about the C programming language today, the book "K&R C Programming Language" is considered to be the most appropriate source for learning the C programming language.

Hello, World

"Hello, World", or "Hello, World" in its original form, was first used by Dennis Ritchie and Brian Kernighan in the K&R C Programming Language book.

This example has become so popular and accepted that almost all programming courses today start with this example.

Dennis Ritchie's Awards

Dennis Ritchie has received most of his awards jointly with Ken Thompson for the development of Unix and the C Programming language. Some of these include:

  • In 1983, they received the Turing Prize, which is recognized as the biggest prize in the world of informatics and the Nobel Prize of the computer world.
  • In 1990, they received the "IEEE Richard W. Hamming Medal", which is given to only 3 people a year.
  • In 1997, he and Ken Thompson were awarded honorary membership by the Computer History Museum.
  • In 1999, they received the National Medal of Technology and Innovation award from then-President Bill Clinton.
  • In 2005, they received an award from the Industrial Research Institute.
  • In 2011, they received the Japan Information and Communication Award.

The Death of Dennis Ritchie

Ritchie was found dead in his home on October 12, 2011, where he lived alone following treatments for prostate cancer and heart disease.


You can listen to the song "Write in C" written by C language developers for Dennis Ritchie, replacing the song "Let it be".

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