Nested Ternary Operators

It’s nearly twenty years since I first learnt to code, and the choice of language (imposed by school, among others) then was C. One of the most fascinating things about C was what was simply called the “ternary operator”, which is kinda similar to the IF statement in Excel, ifelse statement in R and np.where statement in Python.

Basically the ternary operator consisted of a ‘?’ and a ‘:’. It was a statement that took the form of “if this then that else something else”. So, for example, if you had two variables $a$ and $b$, and had to return the maximum of them, you could use the ternary operator to say $a>b?a:b$.

Soon I was attending programming contests, where there would be questions on debugging programs. These would inevitably contain one question on ternary operators. A few years later I started attending job interviews for software engineering positions. The ternary operator questions were still around, except that now it would be common to “nest” ternary operators (include one inside the other). It became a running joke that the only place you’d see nested ternary operators was in software engineering interviews.

The thing with the ternary operator is that while it allows you to write your program in fewer lines of code and make it seem more concise, it makes the code a lot less readable. This in turn makes it hard for people to understand your code, and thus makes it hard to debug. In that sense, using the operator while coding in C is not considered particularly good practice.

It’s nearly 2018 now, and C is not used that much nowadays, so the ternary operator, and the nested ternary operator, have made their exit – even from programming interviews if I’m not wrong. However, people still continue to maintain this practice of writing highly optimised code.

Now, every programmer who thinks he’s a good programmer likes to write efficient code. There’s this sense of elegance about code written in a rather elegant manner, using only a few lines. Sometimes such elegant code is also more efficient, speeding up computation and consuming less memory (think, for example, vectorised operations in R).

The problem, however, is that such elegance comes with a tradeoff with readability. The more optimised a piece of code is, the harder it is for someone else to understand it, and thus the harder it is to debug. And the more complicated the algorithm being coded, the worse it gets.

It makes me think that the reason all those ternary operators used to appear in those software engineering interviews (FYI I’ve never done a software engineering job) is to check if you’re able to read complicated code that others write!