title: golang slice, slicing a slice with slice[a:b:c]
body: <p>I read <a href="http://blog.golang.org/go-slices-usage-and-internals" rel="noreferrer">go slice usage and internals</a> and <a href="http://blog.golang.org/slices" rel="noreferrer">Slice</a> and <a href="https://golang.org/doc/effective_go.html#slices" rel="noreferrer">Effective go#slice</a> but there is nothing about slicing a slice with 3 number like this : <code>slice[a:b:c]</code></p>
  
  <p>For example this code : </p>
  
  <pre><code>package main
  
  import "fmt"
  
  func main() {
      var s = []string{"a", "b", "c", "d", "e", "f", "g"}
      fmt.Println(s[1:2:6], len(s[1:2:6]), cap(s[1:2:6]))
      fmt.Println(s[1:2:5], len(s[1:2:5]), cap(s[1:2:5]))
      fmt.Println(s[1:2], len(s[1:2]), cap(s[1:2]))
  
  }
  </code></pre>
  
  <p><a href="http://play.golang.org/p/up387gsFs8" rel="noreferrer">go playground</a> result is this : </p>
  
  <pre><code>[b] 1 5
  [b] 1 4
  [b] 1 6
  </code></pre>
  
  <p>I can understand that the third one is something about capacity, but what is the exact meaning of this?<br>
  Do I miss something in documents?</p>