Accessing values while iterating points in sensor_msgs::PointCloud2 from sensor_msgs::PointCloud2ConstIterator

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I am writing a node that subscribes to a topic of type sensor_msgs::PointCloud2.

In the callback I want to iterate the points in the point cloud using sensor_msgs::PointCloud2ConstIterator.

This is how I think it should be implemented (which seems to work, no serious testing so far, though):

void callback(sensor_msgs::PointCloud2ConstPtr const& msg) {
    sensor_msgs::PointCloud2ConstIterator<float> iter_x(*msg, "x"),
                                                 iter_y(*msg, "y"),
                                                 iter_z(*msg, "z");
    while (iter_x != iter_x.end()) {
        // TODO: do something with the values of x, y, z
        std::cout << *iter_x << ", " << *iter_y << ", " << *iter_z << "\n";
        ++iter_x; ++iter_y; ++iter_z;
    }
}

Is this about the recommended way of iterating the points in a point cloud?

I've seen there was also an overload of the element access operator[](...). While I was trying to figure out how element access exactly works, I wrote this little callback to get an impression:

void callback(sensor_msgs::PointCloud2ConstPtr const& msg) {
    sensor_msgs::PointCloud2ConstIterator<float> iter_x(*msg, "x");
    std::cout << *iter_x << ", " 
        << iter_x[0] << ", " 
        << iter_x[1] << ", "
        << *(iter_x+1) << "\n";
}

I got an output like this:

1.04852, 1.04852, -1.78216, 1.54717

I wondered, shouldn't the last two values be identical?