Gnome Terminal cannot print the red color in a program using curses

Question

I am trying to get into the ncurses library. I am dissapointed that the Gnome Terminal can print red via ANSI escape characters but not the predefined red from ncurses.

#include <curses.h>

void init_colors() {
    int a;
    for(a = 1; a < COLORS; a++) {
        init_pair(a, a, COLOR_BLACK);
    }
}

void print_colors() {
    int a;
    for(a = 1; a < COLORS; a++) {
        attron(COLOR_PAIR(a));
        mvprintw(a, 0, "color");
        attroff(COLOR_PAIR(a));
    }
}

int main() {
    initscr();
    cbreak();
    noecho();
    curs_set(0);

    if(has_colors()) 
        start_color();          

    init_colors();
    print_colors();
    getch();
    endwin();

    return 0;
}

This should print the word "color" in any default ncurses color, but the second line (init_pair should initialize the second COLOR_PAIR as red) is not printed at all. It seems that Gnome Terminal simply skip this line. How can I fix this?

Can you print any other colors? Or is it just red that fails? — Mooing Duck
@MooingDuck I can print any other of the predefined colors without problems: Including black, green, yellow, blue, magenta, cyan and white. — Markus
This could be a local issue or setting in your gnome-terminal. It works here with 3.14.2. — gpoo

user3629249 user3629249 · Accepted Answer · 2015-04-08T00:15:14

This is a copy of another stackoverflow answer

#include <curses.h>

int main(void) {
    initscr();
    start_color();

    init_pair(1, COLOR_BLACK, COLOR_RED);
    init_pair(2, COLOR_BLACK, COLOR_GREEN);

    attron(COLOR_PAIR(1));
    printw("This should be printed in black with a red background!\n");

    attron(COLOR_PAIR(2));
    printw("And this in a green background!\n");
    refresh();

    getch();

    endwin();
}

Notes

you need to call start_color() after initscr() to use color.
you have to use the COLOR_PAIR macro
to pass a color pair allocated with init_pair to attron et al.
you can't use the color pair 0.
you only have to call refresh() once,
and only if you want your output to be seen at that point,
and you're not calling an input function like getch().

Gnome Terminal cannot print the red color in a program using curses

1 Answers

Notes