title: What does: string $string[, int $length]) mean in PHP?
body: <p>The following statement is taken from the PHP manual online:</p>
  
  <blockquote>
    <p>Int fwrite( resource $handle, string $string[, int $length])</p>
  </blockquote>
  
  <p>I understand that <code>fwrite</code> is a function
  that returns an <code>int</code>, takes a resource called <code>$handle</code>.</p>
  
  <p>But what is: <code>string $string [, int $length ]</code>?</p>
  
  <p>Is that an array? What is the comma for?</p>