title: confusion about file I/O
body: <p>I was asked by an interviewer, the question is simple, <code>find the top 100 from 1 million integers (32-bits)</code>.</p>
  
  <p>When I was solving the question, I thought if I <code>put all the 1 million integers into the memory</code>, that would take up <code>4 MB space</code>.</p>
  
  <p>My question probably has nothing to do with the interview question, but here it is:</p>
  
  <p>if the 1 million integers are store in a file <code>num.txt</code>, and further more, I want to <code>read the all out</code> of file and <code>put them in memory</code> (store them in an array probably), then <code>how many IO will it take</code>?</p>