title: Swift: how add offset to memcpy(...)
body: <p>How to add offset for array for memcpy(...) invocation?</p>
  
  <p>I have array of <code>String</code> :</p>
  
  <pre><code>var source = ["a","b","c","d"]
  var dest = [String](count:n, repeatedValue: "")
  memcpy(&amp;dest, source, UInt(2 * sizeof(String))
  </code></pre>
  
  <p>This copy ["a","b"] to dest. I'ts obvious.
  How can i copy ["b", "c"] ?</p>