Assessing CS1 Design Skills with a String Manipulation Task

This study explores novice programmers' abilities to design and code a string manipulation task in C after one semester of tertiary instruction. String manipulation is an important skill for novice programmers to master as most applications deal with text and/or interact with the user. The analysis shows most novice programmers (88%) were able to sketch their own programming plan to print a word in pyramid style. 53% of students chose to control the printing letter by letter (character level) and 32% updated and printed the word as a whole (string level). However only 6% used string functions, apart from strlen() and strcmp(), to implement their plan. This indicated a low level of transfer from their most recent class activity which focused on the C string library. As expected, not all succeeded to correctly implement their plan: 56% were correct at character level and 63% at string level, resulting in 49% of the whole cohort completing the task. Their code has been thoroughly analysed to identify implementation issues, and logical, syntax and plan errors are reported and discussed.