This work introduces and evaluates ccheck, a lenient automatic grader and C style-checker, to guide students to improve their coding practices. Many computing classes rely heavily on autograders–software that automates grading and alleviates staff workload in classes with large enrollments. At best, autograders offer timely and consistent feedback to students. However, existing autograders primarily judge on functional correctness—they are generally strict and inflexible in marking beginner programming assignments. They tend not to provide feedback on programming style and structure, which instead requires delayed, tedious manual assessment. ccheck, the tool we introduce, aims to address this gap and provide more meaningful, real-time feedback with a pedagogical focus.

We deploy and evaluate ccheck in a class of 440 first-year computing students. Tutors employ the system for marking assistance, while students use the same system for self-evaluation prior to finalizing their submissions. Feedback was solicited through a survey of 76 students and a focus group of the teaching team. 82% of the students surveyed said that the system helped them learn good coding practices, while 75% emphasized that the feedback received from the system is meaningful and helpful. The teaching team focus group related to how they valued the automation of menial marking tasks, which enabled them to direct their time toward other meaningful feedback. Overall, we find that teaching, learning and student experiences are improved through the deployment of ccheck.