can't use push_back for a array ros message in arduino

edit

Arduino code:

#include <ros.h>
#include <geometry_msgs/Pose.h>
#include <geometry_msgs/PoseArray.h>

ros::NodeHandle nh;

geometry_msgs::PoseArray array;
ros::Publisher p("array", &array);

void setup()
{ 
  pinMode(13, OUTPUT);
  nh.initNode();
  nh.advertise(p);
}

void loop()
{  
  geometry_msgs::Pose pose;

  pose.position.x=1;
  pose.position.y=1;
  pose.position.z=1;

  array.poses.push_back(pose);

  p.publish(&array);
  nh.spinOnce();
  delay(10);
}

Here is simple test to publish a PoseArray. When I compile it, I got the errors like:

/Users/Crazymumu/Desktop/array_test_1/array_test_1.ino: In function 'void loop()': array_test_1:37: error: request for member 'push_back' in 'array.geometry_msgs::PoseArray::poses', which is of pointer type 'geometry_msgs::Pose' (maybe you meant to use '->' ?)
array.poses.push_back(pose); ^ exit status 1 request for member 'push_back' in 'array.geometry_msgs::PoseArray::poses', which is of pointer type 'geometry_msgs::Pose' (maybe you meant to use '->' ?)

I am not sure. This should be all right in original ROS environment. Any suggestions? Thanks