Dead code is a bad smell and it appears to be widespread in open-source and commercial software systems. Surprisingly, dead code has received very little empirical attention from the software engineering research community. In this paper, we present a multi-study investigation with an overarching goal to study, from the perspective of researchers and developers, when and why developers introduce dead code, how they perceive and cope with it, and whether dead code is harmful. To this end, we conducted semi-structured interviews with software professionals and four experiments at the University of Basilicata and the College of William & Mary. The results suggest that it is worth studying dead code not only in the maintenance and evolution phases, where our results suggest that dead code is harmful, but also in the design and implementation phases. Our results motivate future work to develop techniques for detecting and removing dead code and suggest that developers should avoid this smell.

中文翻译：

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对死代码的多项研究调查

死代码是一种难闻的气味，它似乎在开源和商业软件系统中很普遍。令人惊讶的是，死代码很少受到软件工程研究社区的实证关注。在本文中，我们提出了一项多研究调查，其总体目标是从研究人员和开发人员的角度研究开发人员何时以及为何引入死代码，他们如何看待和应对死代码，以及死代码是否有害。为此，我们在巴西利卡塔大学和威廉玛丽学院对软件专业人士进行了半结构化访谈和四项实验。结果表明，不仅在维护和进化阶段，研究死代码是值得的，我们的结果表明死代码是有害的，而且还处于设计和实施阶段。我们的结果激励未来的工作开发检测和删除死代码的技术，并建议开发人员应该避免这种气味。