An exploratory study of program comprehension strategies of procedural and object-oriented programmers

This exploratory study examines the nature of program understanding strategies employed during a series of comprehension and maintenance activities carried out over time. Two dimensions of comprehension were examined: the direction of comprehension and the breadth of comprehension. Thirty expert procedural and object-oriented (OO) programmers studied a program and then performed modifications during two sessions held 1 week apart. The results showed that the direction of comprehension was mixed. The OO programmers tended to use a strongly top-down approach to program understanding during the early phase of familiarization with the program but used an increasingly bottom-up approach during the subsequent maintenance tasks. The procedural programmers used a more bottom-up orientation even during the early phase, and this bottom-up approach became even stronger during the maintenance tasks. The breadth of the programmers' comprehension was found to be greater for the procedural programmers than for the object-oriented programmers. However, after carrying out a series of tasks, all programmers had examined the majority of the program code. The results suggest that, regardless of paradigm, expert programmers eventually build a broad systematic, rather than a localized, view of a program over time.