Indices :

#include <stdio.h>
#include <stdint.h>

/* Stub for playground simulation */
#define NUM_LEDS 4

struct led_rgb { uint8_t r; uint8_t g; uint8_t b; };
static struct led_rgb pixels[NUM_LEDS];
static void *strip = NULL;

static void led_strip_update_rgb(void *dev, struct led_rgb *px, int n)
{
    (void)dev;
    printf("LED strip update (%d LEDs):\n", n);
    for (int i = 0; i < n; i++) {
        printf("  LED %d: r=%u g=%u b=%u\n", i, px[i].r, px[i].g, px[i].b);
    }
}

void eteindre_tout(void)
{
    for (int i = 0; i < NUM_LEDS; i++) {
        pixels[i].r = 0;
        pixels[i].g = 0;
        pixels[i].b = 0;
    }
}

void afficher_violet(void)
{
    /* Violet = rouge + bleu */
    for (int i = 0; i < NUM_LEDS; i++) {
        pixels[i].r = 128;
        pixels[i].g = 0;
        pixels[i].b = 128;
    }
    led_strip_update_rgb(strip, pixels, NUM_LEDS);
}

int main(void)
{
    eteindre_tout();
    printf("Apres eteindre_tout:\n");
    for (int i = 0; i < NUM_LEDS; i++) {
        printf("  LED %d: r=%u g=%u b=%u\n", i, pixels[i].r, pixels[i].g, pixels[i].b);
    }
    afficher_violet();
    return 0;
}

Solution copiée dans l'éditeur.