The love/hate relationship with the C preprocessor: An interview study

Flávio Medeiros, Christian Kästner, Márcio Ribeiro, Sarah Nadi, Rohit Gheyi

Research output: Chapter in Book/Report/Conference proceedingConference contribution


The C preprocessor has received strong criticism in academia, among others regarding separation of concerns, error proneness, and code obfuscation, but is widely used in practice. Many (mostly academic) alternatives to the preprocessor exist, but have not been adopted in practice. Since developers continue to use the preprocessor despite all criticism and research, we ask how practitioners perceive the C preprocessor. We performed interviews with 40 developers, used grounded theory to analyze the data, and cross-validated the results with data from a survey among 202 developers, repository mining, and results from previous studies. In particular, we investigated four research questions related to why the preprocessor is still widely used in practice, common problems, alternatives, and the impact of undisciplined annotations. Our study shows that developers are aware of the criticism the C preprocessor receives, but use it nonetheless, mainly for portability and variability. Many developers indicate that they regularly face preprocessorrelated problems and preprocessor-related bugs. The majority of our interviewees do not see any current C-native technologies that can entirely replace the C preprocessor. However, developers tend to mitigate problems with guidelines, even though those guidelines are not enforced consistently. We report the key insights gained from our study and discuss implications for practitioners and researchers on how to better use the C preprocessor to minimize its negative impact.

Original languageEnglish (US)
Title of host publication29th European Conference on Object-Oriented Programming, ECOOP 2015
EditorsJohn Tang Boyland
PublisherSchloss Dagstuhl- Leibniz-Zentrum fur Informatik GmbH, Dagstuhl Publishing
Number of pages24
ISBN (Electronic)9783939897866
StatePublished - Jul 1 2015
Event29th European Conference on Object-Oriented Programming, ECOOP 2015 - Prague, Czech Republic
Duration: Jul 5 2015Jul 10 2015

Publication series

NameLeibniz International Proceedings in Informatics, LIPIcs
ISSN (Print)1868-8969


Conference29th European Conference on Object-Oriented Programming, ECOOP 2015
Country/TerritoryCzech Republic


  • C preprocessor
  • CPP
  • Grounded theory
  • Interviews
  • Surveys

ASJC Scopus subject areas

  • Software


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