Ordering of numeric conditional tests

I’m reading Code Complete and something caught my eye in chapter 19. At first I wanted to argue with it, but the more I thought about it the more I liked it.

The idea concerns the situation where you need to test if a variable satisfies an inequality, for example, if you need to know if min < n < max. I’ve always done it like this:

```if (x > min) && (x < max)
// -or-
if (x < lower) || (x > higher)```

I did it this way because I liked having the comparison variable on the left and the constant on the right. McConnell suggested that the organization should look more like the inequality:

```if (min < x) && (x < max)
// -or-
if (x < lower) || (higher < x)```

I initially rebelled against this part of the chapter simply because it was not what I liked, but the more I think about it the more I like it. Almost every time I have to code an inequality like this I make a mistake, and I always write extra tests for these cases. I think if I start writing the conditions this way, I can increase the probability that I’ll get it right the first time.

One thought on “Ordering of numeric conditional tests”

1. The second way is how my professors tend to write conditions like that, and I never really thought about it I guess, I used to do it the first way because it seemed more symmetrical, but at some point I realized that the second way does more closely reflect set notation, and it makes more sense to think of it logically as one condition of ” min < value < max ” rather than two separate tests.