Why prefer start + (end - start) / 2 over (start + end) / 2 when calculating the middle of an array?

Question

I\'ve seen programmers use the formula

mid = start + (end - start) / 2

instead of using the simpler formula

mid = (start +          


        

Answer 1

To add to what others have already said, the first one explains its meaning clearer to those less mathematically minded:

mid = start + (end - start) / 2

reads as:

mid equals start plus half of the length.

whereas:

mid = (start + end) / 2

reads as:

mid equals half of start plus end

Which does not seem as clear as the first, at least when expressed like that.

as Kos pointed out it can also read:

mid equals the average of start and end

Which is clearer but still not, at least in my opinion, as clear as the first.