title: What is the difference between pass-by-result and pass-by-value-result?
body: <p>I found this explanation:</p>
  <blockquote>
  <p>call by value: copy going into the procedure</p>
  <p>call by result: copy going out of the procedure</p>
  <p>call by value result: copy going in, and again going out</p>
  </blockquote>
  <p>But I don't understand, if we don't copy input, than how call by result differ from call by reference and for what we are make copy in the end of procedure. Can anybody explain?</p>