## 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!

## Programming back to the 1970s

I learnt to write computer code circa 1998, at a time when resources were plenty. I had a computer of my own – an assembled desktop with a 386 processor and RAM that was measured in MBs. It wasn’t particularly powerful, but it was more than adequate to handle the programs I was trying to write.

I wasn’t trying to process large amounts of data. Even when the algorithms were complex, they weren’t that complex. Most code ran in a matter of minutes, which meant that I didn’t need to bother about getting the code right the first time round – apart from for examination purposes. I could iterate and slowly get things right.

This was markedly different from how people programmed back in the 1970s, when computing resource was scarce and people had to mostly write code on paper. Time had to be booked at computer terminals, when the code would be copied onto the computers, and then run. The amount of time it took for the code to run meant that you had to get it right the first time round. Any mistake meant standing in line at the terminal again, and further time to run  the code.

The problem was particularly dire in the USSR, where the planned economy meant that the shortages of computer resources were shorter. This has been cited as a reason as to why Russian programmers who migrated to the US were prized – they had practice in writing code that worked for the first time.

Anyway, the point of this post is that coding became progressively easier through the second half of the 20th century, when Moore’s Law was in operation, and computers became faster, smaller and significantly more abundant.

This process continues – computers continue to become better and more abundant – smartphones are nothing but computers. On the other side, however, as storage has gotten cheap and data capture has gotten easier, data sources are significantly larger now than they were a decade or two back.

So if you are trying to write code that uses a large amount of data, it means that each run can take a significant amount of time. When the data size reaches big data proportions (when it all can’t be processed on a single computer), the problem is more complex.

And in that sense, every time you want to run a piece of code, however simple it is, execution takes a long time. This has made bugs much more expensive again – the amount of time programs take to run means that you lose a lot of time in debugging and rewriting your code.

It’s like being in the 1970s all over again!