Traffic light state machine using an enum in C Solution, output & explanation

#include <stdio.h>

enum light { RED, GREEN, YELLOW, LIGHT_COUNT };

static const char *light_name[LIGHT_COUNT] = {"RED", "GREEN", "YELLOW"};
static const int seconds[LIGHT_COUNT] = {30, 25, 5};

enum light next(enum light l) {
    switch (l) {
    case RED:    return GREEN;
    case GREEN:  return YELLOW;
    case YELLOW: return RED;
    default:     return RED;          /* never reached: keeps the compiler happy */
    }
}

int main(void) {
    enum light l = RED;
    for (int step = 0; step < 5; step++) {
        printf("%-6s %2ds\n", light_name[l], seconds[l]);
        l = next(l);
    }
    return 0;
}

RED    30s
GREEN  25s
YELLOW  5s
RED    30s
GREEN  25s