  Learning new programming skills requires tailored guidance. With the
emergence of advanced Natural Language Generation models like the ChatGPT API,
there is now a possibility of creating a convenient and personalized tutoring
system with AI for computer science education. This paper presents GPTutor, a
ChatGPT-powered programming tool, which is a Visual Studio Code extension using
the ChatGPT API to provide programming code explanations. By integrating Visual
Studio Code API, GPTutor can comprehensively analyze the provided code by
referencing the relevant source codes. As a result, GPTutor can use designed
prompts to explain the selected code with a pop-up message. GPTutor is now
published at the Visual Studio Code Extension Marketplace, and its source code
is openly accessible on GitHub. Preliminary evaluation indicates that GPTutor
delivers the most concise and accurate explanations compared to vanilla ChatGPT
and GitHub Copilot. Moreover, the feedback from students and teachers indicated
that GPTutor is user-friendly and can explain given codes satisfactorily.
Finally, we discuss possible future research directions for GPTutor. This
includes enhancing its performance and personalization via further prompt
programming, as well as evaluating the effectiveness of GPTutor with real
users.
