title: C Struct array member without specific length
body: <p>I have encountered this piece of code:</p>
  
  <pre><code>struct test                   
  {                                        
   uint32       num_fields;            
   char array_field [];               
  }; 
  </code></pre>
  
  <p>How can I understand <code>array_field</code>? Is this a gcc extension for the C language?</p>