Charles Antony Richard Hoare, known as Tony Hoare, is a British computer scientist whose work shaped both practical programming and the theory of program correctness. His Microsoft Research profile records that he is known for “his sorting and selection algorithms, for example, Quicksort and Find,” and for the body of logic and language theory that followed.
Hoare invented Quicksort around 1959 to 1961 while working on machine translation, and published it as “Quicksort” in The Computer Journal in 1962. The algorithm sorts by partitioning data around a chosen pivot and then sorting the parts, and it became one of the most widely used sorting methods ever devised.
Beyond sorting, Hoare developed Hoare logic, a formal system for reasoning about whether a program meets its specification, and Communicating Sequential Processes (CSP), a model for describing concurrent systems that pass messages to one another. His Microsoft Research profile lists both among his central achievements, alongside his later work on verified software.
Hoare received the A. M. Turing Award from the Association for Computing Machinery, recognized for the year 1980, for his fundamental contributions to the definition and design of programming languages. In a widely cited 2009 talk he reflected on having added the null reference to ALGOL W in 1965, calling it “my billion-dollar mistake” for the long trail of errors and crashes it later caused.