An Empirical Study on the Readability of Regular Expressions: Textual Versus Graphical

Although the readability of source code plays an important role in software construction, not many studies are available that do actually compare the impact of different notations on the readability of source code. Among the huge set of possible languages to be studied, one language is frequently used in education as well as in practice: regular expressions. This paper introduces a randomized controlled trial performed on 22 participants that compares two different notations for regular expressions: a textual and a graphical one. It shows that a regular expression's length as well as the notation (textual vs. graphical) has a strong effect on the regular expression's readability while the participants' background showed no measurable effect. On average, the time required by the participants to answer questions about shortest words using the textual representation was almost three times higher than the time it took for answering such questions using the graphical representation.