ABSTRACT

Quite a number of papers have discussed the problems of identifying unstructured programs and turning them into structured programs. Most of the papers, however, are based on intuitive arguments rather than on formal proofs. The identification of program unstructuredness has remained a difficult task. In this paper we formally study the properties of skeletons, modules, branches, iteration exits and entry nodes in program flowgraphs. We prove that two simple conditions are sufficient and necessary for the identification of unstructuredness.

1. A preliminary version of this paper, entitled "On the detection of unstructuredness in flowgraphs", was published in Information Processing Letters 25 (3): 189-193 (1987). Part of this research was done at the London School of Economics under a Commonwealth Academic Staff Scholarship. 2. Department of Computer Science, The University of Hong Kong, Pokfulam, Hong Kong. Email:

EVERY VISITOR COUNTS: