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I am not able to run a node.

asked 2019-12-01 11:04:44 -0600

ammaralam221 gravatar image

I am running ros kinetic on ubuntu 16.

While running a file hello_world.cpp, I get the following error

/media/ammar/New Volume/December/ros_directory/src/agitr_book/src/hello_world.cpp: line 2: syntax error near unexpected token `('
/media/ammar/New Volume/December/ros_directory/src/agitr_book/src/hello_world.cpp: line 2: `int main (int argc, char **argv)'

This is the code in hello_world.cpp

#include "ros/ros.h"
int main (int argc, char **argv)
{
    //intializes ros client library
    //last parameter is a string containing
    //deafult name of the node
    //can be overwridden by a launch file
    //call this once at the beginning of the program
    ros::init(argc, argv, "hello_ros");


    //establishes this program as a ros node
    //nh is the main mechanism that the program
    //will use to interact with the ROS system
    //creating this object registers the program
    //as a node at ros master
    ros::NodeHandle nh;


    //generates an informational message
    //send to console screen
    ROS_INFO_STREAM("HELLO_ROS");
}

I don't think, there is anything wrong the code as I am following it along with a book. I believe the problem is with the #include line but i don't know what?? If anyone could help me, it will be appreciated.

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Comments

Since your node is C++, you need to compile it before you run it.

ahendrix gravatar image ahendrix  ( 2019-12-01 12:32:39 -0600 )edit

1 Answer

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answered 2019-12-01 12:24:47 -0600

I ran your code and found no issues... (ubuntu 16.04 with ROS kinetic), however you are not publishing your CMakeLists.txt neither your package.xml files. Here are mine for reference:

CMakeLists.txt

cmake_minimum_required(VERSION 2.8.3)
project(hello_world)

## Compile as C++11, supported in ROS Kinetic and newer
add_compile_options(-std=c++11)

find_package(catkin REQUIRED
COMPONENTS
    roscpp
)

catkin_package(
CATKIN_DEPENDS
)

add_executable(hello_world ros/src/hello_world.cpp)
target_link_libraries(hello_world ${catkin_LIBRARIES})

package.xml

<?xml version="1.0"?>
<package>
<name>hello_world</name>
<version>1.0.0</version>
<description>
    hello world tutorial
</description>

<license>GPLv3</license>

<author email="olima@isr.tecnico.ulisboa.pt">Oscar Lima</author>
<maintainer email="olima@isr.tecnico.ulisboa.pt">Oscar Lima</maintainer>

<buildtool_depend>catkin</buildtool_depend>

<build_depend>roscpp</build_depend>

</package>

Compile your code

catkin build --this

Very important: source your workspace again after having compiled

source ~/my_catkin_ws/devel/setup.bash

Run the code

roscore
rosrun hello_world hello_world

You should now be able to see the desired output

[ INFO] [/hello_ros]: HELLO_ROS
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Comments

Thanks for your help. I found what I was doing wrong, there was a problem with the rosrun command I was using

rosrun agitr_book hello_world.cpp

there shouldn't be a .cpp in this, the correct command is

rosrun agitr_book hello_world
ammaralam221 gravatar image ammaralam221  ( 2019-12-02 05:35:40 -0600 )edit

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Asked: 2019-12-01 11:04:44 -0600

Seen: 318 times

Last updated: Dec 01 '19