/logical comparison/ int greater_abs(int num, int x){ return (num > x) || (num+x < 0); }
/squared approach/ int greater_abs2(int num, int x){ return num*num > x; }
See it by yourself, with (and without) optimizations: https://godbolt.org/
What would happen if x is a compile-time constant?
Godbolt uses whatever compilers, targets, and optimisations you ask it to.
It is, in fact, a very useful tool for comparing different compilers, architectures, and optimization settings.
In practice, just writing "abs(num) > x" gives quite good machine code, and it does so without introducing hard-to-see bugs.
In the 2nd, which I assume should be
{ return num*num > x * x; }
How frequently am I calling `abs`?
Well if that were the case, I’d use a profiler to see if spending time on optimizing ‘abs’ would realistically be worth it.