The C preprocessor cpp is a powerful and
language-independent tool, widely used to implement
variable software in different programming
languages (C, C++) using conditional compilation.
Preprocessor annotations can used on different
levels of granularity such as functions or statements.
In this paper, we investigate whether there
is a relation between code clones and preprocessor
annotations. Specifically, we address the question
whether the discipline of annotation has an effect
on code clones. To this end, we perform a case
study on fifteen different C programs and analyze
them regarding code clones and #ifdef occurrences.
We found only minor effects of annotations
on code clones but a relationship between
annotations that align with the code structure (and
code clones). With this work, we provide new
insights why code clones occur in C programs.
Furthermore, the results can support the decision
whether it is beneficial to remove clones or not.