Can we use arrays for multiple publish topics in ros?

Question

So i was working on some ros based UAV simulation and it just struck me when I had to initialize separate publishers for each UAV. Is it possible to make an array of such publishers and then reference them by just using their index number? I know I should just do it and try it, but I guessed asking here would be a faster option:)

Answer 1

Yes this is possible by collecting multiple ros::Publishers in containers. Here is a small example using an array:

#include <ros/ros.h>

#include <std_msgs/String.h>

int main(int argc, char *argv[])
{
  ros::init(argc, argv, "test_node");
  ros::NodeHandle nh;
  ros::WallTimer timer;

  //Create publishers
  std::array<ros::Publisher, 3> publishers;
  for (size_t i = 0; i < publishers.size(); i++)
  {
    std::stringstream topic_name;
    topic_name << "topic" << i;
    publishers[i] = nh.advertise<std_msgs::String>(topic_name.str(), 0);
  }

  //Publish
  ros::Rate r(1);
  std_msgs::String msg;
  while (nh.ok())
  {
    std::stringstream message;
    message << "Hello World " << ros::Time::now();
    msg.data = message.str();
    for (size_t i = 0; i < publishers.size(); i++)
    {
      publishers[i].publish(msg);
    }

    ros::spinOnce();
    r.sleep();
  }

  return 0;
}

The node advertises the three topics

• /topic0
• /topic1
• /topic2

and publishes a simple string like Hello World 1562571209.130936883 with a rate of 1 Hz.