Question: how to work in 'utilities' folder ? The compiler can't find the path for headers

[gui.d]

In this course, we are suggested to use the ‘utilities folder’ to work. So I did try. However when I try to compile, the compiler can’t find the path to included headers.

Here I tried to compile the solution of exercise 2.1 which I copied in the file named 'unit2_exercise21.cpp" in the folder ‘utilities’.

So I tried adding the path in the script. And it was not better.

#include "../rosbot_control/include/rosbot_control/rosbot_class.h"

I tried other combination without success.
I tried to look online, but I am not sure of what I am doing.

Could someone be kind other to help me out ?

Thank you

[duckfrost2]

Just tried in the course it seems to work. So steps to reproduce:

1. You nee dto place the code inside the /home/user/catkin_ws/src/cpp_course_repo/c_scripts/src/unit2_exercise.cpp

2. The code is

#include “rosbot_control/rosbot_class.h”
#include <ros/ros.h>

int main(int argc, char **argv) {
ros::init(argc, argv, “rosbot_node”);

RosbotClass rosbot;

rosbot.move_forward(5.0);

float X_limit = 10.0;
float x = rosbot.get_position(1);
ROS_INFO_STREAM("X reached: " << x);

if (x >= X_limit) {
rosbot.stop_moving();
} else {
rosbot.move_backwards(5.0);
rosbot.stop_moving();
}

return 0;
}

3. You have to catkin make like so:

cd ~/catkin_ws
catkin_make
rosrun rosrun c_scripts unit2_exercise

The robot should go forwards and then backwards

Please elaborate if this didn’t work

[gui.d]

Thank you for your quick answer

Yes I can follow the courses’ steps but what if I wanted to work in ‘utilities’ ?

I want to organise my folder my own way in utilities without having to call catkin_make but compiled the code with ‘g++…’ and run with ./code_compiled

How could I do that ?

[ralves]

Hi @gui.d,

I’m happy to see that you want to know the inner details of compiling a program, which shows that you are aiming for perfect stature when it comes to understanding C++.

I just created a main.cpp file with the following content:

#include "geometry_msgs/Twist.h"
#include <stdio.h>

int main() {

    printf("The Construct: Where Your Robotics Career Happens \n");
    return 0;
}

In order to compile it, I just had to pass the -I parameter.
According to the docs:

-I dir
Add the directory dir to the list of directories to be searched for header files.

The final command in my case was:

g++ -std=c++11 main.cpp -I /opt/ros/noetic/include/ -o compiled 

As you can see, I told g++ to search for geometry_msgs at /opt/ros/noetic/include/.

Please let me know us know if you have more questions.

[gui.d]

Hi @ralves ,

Thank you for your help.

As you explained, I added the -I in the command, along side with the directory, which gives me the follwoing command line:

g++ -std=c++11 unit2_exercise21.cpp -I /catkin_ws/src/cpp_course_repo/rosbot_control/include/ -o compiled

My folder having the follwing architecture:

The line of command was unsuccessful (I tried a few variations for the path, here is one)

What did I do wrong ?

Thank you for your time

[ralves]

Hi @gui.d ,

the path to catkin_ws is wrong.

Rather than

 /catkin_ws/src/cpp_course_repo/rosbot_control/include/ 

You have to use either:

 ~/catkin_ws/src/cpp_course_repo/rosbot_control/include/ 

or

 /home/user/catkin_ws/src/cpp_course_repo/rosbot_control/include/ 

If you don’t understand this point, please take the Linux course that is freely available in our platform.