Software analysis by code clones in open source software

The code clone (a duplicated code section in the source files of software) is one of the factors that complicate software maintenance. However, few empirical studies have analyzed the status quo of code clones. In this paper we conduct an extensive analysis of code clones using 125 packages of open source software written in C language, and suggest guidelines for the allowable production of code clones. Our results showed 11.3% as the average CRate (clone inclusion rate). For software packages that did not include automatically generated code, the CRate was 9.7%, the in-module CRate 8.2%, and the inter-module CRate 1.3%. These rates can be used as criteria for the allowable amount of code clone production. This paper also presents our findings on factors of code clone production, the influence of code clone production on maintainability, and removal methods.