I would not let that line pass code review. Obviously. However, it is an appropriate example if your goal is to teach the intricacies of the C language. You're

I would not let that line pass code review. Obviously. However, it is an appropriate example if your goal is to teach the intricacies of the C language. You're right that if you provide such an example this early, it could perhaps use some additional commentary. Not only is that confusingly cutesy, but largeA[i] is a double. That was the point of the exercise: !! is an idiom to convert to boolean (which happen to be integral in C) and something a C programmer (or JavaScript programmer, for that matter) should be familiar with. This is flatly untrue on x86 and I suspect many other architectures. Agreed.