Mid point in divide and conquer algorithm implementations

Question

I've seen many implementations using below to find mid point of two indices:

int mid = lo + (hi - lo) / 2;

instead of

int mid = (lo + hi) / 2;

Mathematically, I see no difference and yet, I've never seen anyone using the below one. Is there a difference between the two computationally?

Answer 1

There exist a maximum positive value for a 32-bit signed binary integer in computing.

We assume this value is 100.

int lo = 60;
int hi = 80;

then lo + hi = 60 + 80 = 140 > 100, it is dangerous to do so because it will cause a integer overflow error.