Traffic Light

A traffic light cycles through a fixed set of states.

traffic_light.c

#include <stdio.h>

enum LightState {
    LIGHT_RED,
    LIGHT_GREEN,
    LIGHT_YELLOW
};

enum LightState nextLight(enum LightState state) {
    if (state == LIGHT_RED) {
        return LIGHT_GREEN;
    }
    if (state == LIGHT_GREEN) {
        return LIGHT_YELLOW;
    }
    return LIGHT_RED;
}

int main(void) {
    int ticks = ;
    enum LightState state = LIGHT_RED;

    for (int i = 0; i < ticks; i++) {
        state = nextLight(state);
    }

    printf("ticks=%d light=%d\n", ticks, state);
    return 0;
}

#include <stdio.h>

enum LightState {
    LIGHT_RED,
    LIGHT_GREEN,
    LIGHT_YELLOW
};

enum LightState nextLight(enum LightState state) {
    if (state == LIGHT_RED) {
        return LIGHT_GREEN;
    }
    if (state == LIGHT_GREEN) {
        return LIGHT_YELLOW;
    }
    return LIGHT_RED;
}

int main(void) {
    int ticks = ;
    enum LightState state = LIGHT_RED;

    for (int i = 0; i < ticks; i++) {
        state = nextLight(state);
    }

    printf("ticks=%d light=%d\n", ticks, state);
    return 0;
}

#include <stdio.h>

enum LightState {
    LIGHT_RED,
    LIGHT_GREEN,
    LIGHT_YELLOW
};

enum LightState nextLight(enum LightState state) {
    if (state == LIGHT_RED) {
        return LIGHT_GREEN;
    }
    if (state == LIGHT_GREEN) {
        return LIGHT_YELLOW;
    }
    return LIGHT_RED;
}

int main(void) {
    int ticks = ;
    enum LightState state = LIGHT_RED;

    for (int i = 0; i < ticks; i++) {
        state = nextLight(state);
    }

    printf("ticks=%d light=%d\n", ticks, state);
    return 0;
}

cycle A cycle returns to the first state after the final state.

transition The transition helper keeps the next-state rule separate from the loop.