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

start + (end-start) / 2 can avoid possible overflow, for example start = 2^20 and end = 2^30