Showing papers by "C. A. R. Hoare published in 1971"

Procedures and parameters: An axiomatic approach

Abstract: It has been suggested, Hoare (1969), that an axiomatic approach to formal language definition might simultaneously contribute to the clarity and reliability of programs expressed in the language, and to the efficiency of their translation and execution on an electronic digital computer. This paper gives an exa~Lple of the application of the axiomatic method to the definition of procedure and parameter passing features of a high-level progr~mning language. It reveals that ease of demonstrating program correctness and high efficiency of implementation may be achieved simultaneously, provided that the programmer is willing to observe a certain familiar and natural discipline in his use of parameters.

Proof of a program: FIND

Abstract: A proof is given of the correctness of the algorithm “Find.” First, an informal description is given of the purpose of the program and the method used. A systematic technique is described for constructing the program proof during the process of coding it, in such a way as to prevent the intrusion of logical errors. The proof of termination is treated as a separate exercise. Finally, some conclusions relating to general programming methodology are drawn.