NCurses getch always returns ERR (-1) - c++

Question

I've just started to work with ROS and I'm trying to write a node that publish keys in a topic.
I have created a node on a Linux Ubuntu 16.04.4 using ncurses.
This is my code:
#include <curses.h>
#include "ros/ros.h"
#include "std_msgs/String.h"
#include <sstream>
int main(int argc, char **argv)
{
int ch;
nodelay(stdscr, TRUE);
ros::init(argc, argv, "keyboard_driver");
ros::NodeHandle n;
ros::Publisher key_pub = n.advertise<std_msgs::String>("keys", 1);
ros::Rate loop_rate(100);
while (ros::ok())
{
std_msgs::String msg;
std::stringstream ss;
if ((ch = getch()) != ERR)
{
ss << ch;
std::cout << ch;
msg.data = ss.str();
ROS_INFO("%s", msg.data.c_str());
key_pub.publish(msg);
}
ros::spinOnce();
loop_rate.sleep();
}
return 0;
}
I'm using ncurses to avoid terminal buffer.
The topic appears, but I don't get anything if, in another terminal, I run this command:
rostopic echo /keys
Debugging it I have found that getch() always return -1.
How can I do to make it work?
UPDATE
I have tried this small program, and it doesn't print anything:
#include <iostream>
#include <curses.h>
int main(int argc, char **argv)
{
int ch;
cbreak();
nodelay(stdscr, TRUE);
for(;;)
{
if ((ch = getch()) != ERR)
{
std::cout << ch;
}
}
return 0;
}

Answer 1

You've set nodelay so getch will return immediately with ERR if there's no data ready from the terminal. That's why getch is returning -1 (ERR). You haven't set cbreak or raw to disable terminal buffering, so you're still getting that -- no data will come from the terminal until Enter is hit.
So add a call to cbreak() at the start (just before or after the call to nodelay()) and it should work as you expect.

Answer 2

To use getch() you have to do the following:
#include <iostream>
#include <curses.h>
#include <signal.h>
#include <stdlib.h>
void quit(int sig)
{
endwin();
exit(0);
}
int main(int argc, char **argv)
{
int ch;
signal(SIGINT,quit);
initscr();
cbreak();
nodelay(stdscr, TRUE);
for(;;)
{
if ((ch = getch()) != ERR)
{
std::cout << ch;
}
}
return 0;
}
I forget to add initscr(); call at the beginning and endwin(); at the end of the program.
More info about how to use ncurses library here.