Overflow issues when implementing math formulas

Question

I heard that, when computing mean value, start+(end-start)/2 differs from (start+end)/2 because the latter can cause overflow. I do not quite understand why this second one

Answer 1

In Binary Search, we will write the following code:

if(start > end){
   return;
}
int mid = start + (end - start) / 2;

By using start + (end - start) / 2, we can avoid the problems which are pointed by @dasblinkenlight

if we use (start + end) / 2, it will overflow as shown by dasblinkenlight