Linux terminal program will let you enter keys without pressing `enter`

key_press.cpp

/* I took the code at www.flipcode.com/archives/_kbhit_for_linux.shtml and refactored it to suit my needs.
 * Usually a terminal program will have an input buffer and will wait until it finds a carriage return (enter) to process the buffer.
 * This code allows you to enter keys without pressing enter, and is useful for a robot project of mine (to give the robot instructions without pressing enter).
 *
 * This is tested and working on Linux (Arch, Mint) and Mac osx.
 *
 * g++ -std=c++14 key_press.cpp -o key_press
 */

#include <iostream>
#include <unistd.h>
#include <termios.h>
#include <sys/ioctl.h>

int get_number_of_chars()
{
    static const int STDIN = 0;
    int bytesWaiting;
    ioctl(STDIN, FIONREAD, &bytesWaiting);
    return bytesWaiting;
}

int prevent_wait_for_EOL()
{
    static const int STDIN = 0;
    termios term;
    tcgetattr(STDIN, &term);
    term.c_lflag &= ~ICANON;
    tcsetattr(STDIN, TCSANOW, &term);
}

int get_last_char_in_buffer(int number_chars_in_buffer)
{
    int ch;
    while(number_chars_in_buffer > 0)
    {
        ch = std::cin.get();
        number_chars_in_buffer = number_chars_in_buffer - 1;
    }
    return ch;
}

int main(int argc, char** argv) {
    prevent_wait_for_EOL();

    while (true) {
        usleep(1000000);
        int number_chars_in_buffer = get_number_of_chars();
        if(number_chars_in_buffer > 0)
        {
            int ch = get_last_char_in_buffer(number_chars_in_buffer);
            std::cout<<"\nDo something with "<< ch<< std::endl;
        }
    }

    return 0;
}