title: java buf[--pos] = (byte)b Please, explain me what is in the square brackets
body: <p>I'm reading sourcecode of PushbackInputStream to gain my understand about unread() method: <a href="http://javasourcecode.org/html/open-source/jdk/jdk-6u23/java/io/PushbackInputStream.java.html" rel="nofollow">http://javasourcecode.org/html/open-source/jdk/jdk-6u23/java/io/PushbackInputStream.java.html</a> but on the line 194: buf[--pos] = (byte)b makes me don't understand what that said.
  Can anyone tell me the meaning of --pos in that line?
  Thanks in advance.</p>
  
  <p>Ps: I even try to code this:</p>
  
  <pre><code>class Test2 {
  public static void main(String[] args) {
      char[] c = { 'd', 'e', 'c', 'a', 'f', 'f', 'e',
              'i', 'n', 'a', 't', 'e', 'd' };
      char temp = 'o';
      c[--1] = tmp;
   }
  }
  </code></pre>
  
  <p>but eclipse tells me: invalid argument operation</p>