Having trouble sending a message to ROS - linux

Question

I am pretty new in ROS. I am just trying to publish a message to a node in a linux server with this code:
#include "stdafx.h"
#include "ros.h"
#include <string>
#include <stdio.h>
#include <Windows.h>
using std::string;
int _tmain(int argc, _TCHAR * argv[])
{
ros::NodeHandle nh;
char *ros_master = "*.*.*.*";
printf("Connecting to server at %s\n", ros_master);
nh.initNode(ros_master);
printf("Advertising cmd_vel message\n");
string sent = "Hello robot";
ros::Publisher cmd_vel_pub("try", sent);
nh.advertise(cmd_vel_pub);
printf("All done!\n");
return 0;
}
The compiler gives me these errors:
Error C2664 'ros::Publisher::Publisher(ros::Publisher &&)': cannot convert argument 2 from 'std::string' to 'ros::Msg *' LeapMotion c:\users\vive-vr-pc\documents\visual studio 2015\projects\leapmotion\leapmotion\leapmotion.cpp 22
Error (active) no instance of constructor "ros::Publisher::Publisher" matches the argument list LeapMotion c:\Users\Vive-VR-PC\Documents\Visual Studio 2015\Projects\LeapMotion\LeapMotion\LeapMotion.cpp 22
I am on Visual Studio and there aren't a lot of tutorial from windows to linux, so I am confused on what to do. Many thanks for the help! :D

Answer 1

Take a look at the Hello World example. You cannot send types which are not defined as messages, i.e. std::string is not a ros message type. What you need is
#include <std_msgs/String.h>
Define and fill the string messages
std_msgs::String sent;
ros::Publisher cmd_vel_pub("try", &sent);
nh.advertise(cmd_vel_pub);
ros::Rate r(1); // once a second
sent.data = "Hello robot";
while (n.ok()){
cmd_vel_pun.publish(sent);
ros::spinOnce();
r.sleep();
}
Check out this blabbler example and these tutorials.