Implementation

The Boolean array i$is\_prime[]$ of Boolean is initialized to $true$ and denotes that all numbers are assumed prime initially and marks them $false$ as we proceed.

We start with $i=2$ and only go up to $ceil(\sqrt{N})$ as explained in previous chapter.

Instead of comparing as $i <= \sqrt(N)$, we are comparing as $i*i <= N$. It’s essentially the same comparison and we avoid dealing with the floating-point variable.