title: Request for member 'resize' in Float64MultiArray which is of non-class type
body: <p>I'm trying to compile a C++ Arduino sketch that uses the ROS data type <a href="http://docs.ros.org/api/std_msgs/html/msg/Float64MultiArray.html" rel="nofollow noreferrer">Float64MultiArray</a>, and some <a href="http://answers.ros.org/question/232659/assign-c-array-to-ros-msg-array/?answer=232706#post-id-232706" rel="nofollow noreferrer">examples</a> say you're supposed to initialize it like:</p>
  
  <pre><code>std_msgs::Float64MultiArray array_msg;
  array_msg.data.resize(9);
  </code></pre>
  
  <p>However, trying to compile my minimal sketch:</p>
  
  <pre><code>#include &lt;std_msgs/Float64MultiArray.h&gt;
  
  std_msgs::Float64MultiArray vec3_msg;
  
  void setup() {
      vec3_msg.data.resize(3);
  }
  
  void loop() {
  }
  </code></pre>
  
  <p>gives me the error:</p>
  
  <pre><code>main.ino: In function 'void setup()':
  main.ino:6:19: error: request for member 'resize' in 'vec3_msg.std_msgs::Float64MultiArray::data', which is of non-class type 'std_msgs::Float64MultiArray::_data_type* {aka float*}'
       vec3_msg.data.resize(3);
                     ^
  </code></pre>
  
  <p>What am I doing wrong?</p>