Meaningful Identifier Names: The Case of Single-Letter Variables

It is widely accepted that variable names in computer programs should be meaningful, and that this aids program comprehension. 'Meaningful' is commonly interpreted as favoring long descriptive names. However, there is at least some use of short and even single-letter names: using 'i' in loops is very common, and we show (by extracting variable names from 1000 popular github projects in 5 languages) that some other letters are also widely used. In addition, controlled experiments with different versions of the same functions (specifically, different variable names) failed to show significant differences in ability to modify the code. Finally, an online survey showed that certain letters are strongly associated with certain types and meanings. This implies that a single letter can in fact convey meaning. The conclusion from all this is that single letter variables can indeed be used beneficially in certain cases, leading to more concise code.