title: Golang size of []byte in int64
body: <pre><code>//data = file in []byte 
  length := len(data)
  </code></pre>
  
  <p><code>length</code> is in type <code>int</code>. I need to find the length in <code>int64</code>. I only have the <code>[]byte</code> data of the file. How can I find the size of data in <code>int64</code>?</p>