Abstract
Software maintenance tasks have become more and more difficult because of the massive scale and complexity of software systems. Code clones are regarded as one of the factors that makes software maintenance more difficult, which makes code clones as a hot research topic on the research area of software engineering. However, the basis that clones are harmful for software maintenance is countered by some opinions. One of them is that code reuse by copy-and-paste operations, which is regarded as a major cause of creation of clones, can promote rapid engineering of software systems. Another opinion is that some research results revealed that not all clones are harmful for software maintenance. These opinions show a high motivation for clone management. This paper presents a survey on research of code clones that is useful for effective clone maintenance.
