Simple warning light flashing in your terminal. Written in C++17 with ncurses.

warn-light.cc

/*
  Simple warning light flashing in your terminal.

  Compile with the following arguments:
    <YOUR COMPILER> --std=c++17 -O2 -lcurses -o warn-light warn-light.cc
*/

#include <ncurses.h>
#include <stdint.h>
#include <unistd.h>

#include <array>
#include <iostream>

constexpr uint64_t kDelayTimeMs = 100;

void fillScreenWithColorPair(int colorPair) {
  int height, width;
  getmaxyx(stdscr, height, width);

  attron(COLOR_PAIR(colorPair));
  for (int y = 0; y < height; y++) {
    for (int x = 0; x < width; x++) {
      mvaddch(y, x, ' ');
    }
  }
  attroff(COLOR_PAIR(colorPair));
  refresh();
}

int curses_main() {
  // Curcularly display these color pairs
  std::array<int, 6> colorPairs = {0, 1, 0, 2, 0, 3};

  for (int i = 0;; i = (i + 1) % colorPairs.size()) {
    fillScreenWithColorPair(colorPairs[i]);
    usleep(1000 * kDelayTimeMs);
  }

  return 0;
}

int main() {
  // Initialize the terminal
  initscr();
  cbreak();
  noecho();
  keypad(stdscr, true);
  clear();

  // Initialize the color mechanism
  start_color();
  use_default_colors();

  const auto dummyColor = COLOR_BLACK;
  init_pair(1, dummyColor, COLOR_GREEN);
  init_pair(2, dummyColor, COLOR_RED);
  init_pair(3, dummyColor, COLOR_BLUE);

  // Check if colors are too few
  if (COLORS <= 2) {
    endwin();
    std::cout << "ERROR: Too few colors.\n" << std::endl;
    return 1;
  }

  int res = curses_main();

  endwin();
  return res;
}