Make blocks of 10 LEDs

Question

I want 10 red LEDs and next 10 white LEDs, and that repeated until I reach the end of the LED string.

This is the worst code, but it works.

What is the right way to do this? It must be very simple, but I can't figure it out

void Brabant() {
  for (int i = 0; i < NUM_LEDS; i = i + 20) {
    if (i < NUM_LEDS) {
      leds[i] = CRGB::Red;
      leds[i + 1] = CRGB::Red;
      leds[i + 2] = CRGB::Red;
      leds[i + 3] = CRGB::Red;
      leds[i + 4] = CRGB::Red;
      leds[i + 5] = CRGB::Red;
      leds[i + 6] = CRGB::Red;
      leds[i + 7] = CRGB::Red;
      leds[i + 8] = CRGB::Red;
      leds[i + 9] = CRGB::Red;
      FastLED.show();
    }
  }
  for (int i = 10; i < NUM_LEDS; i = i + 20) {
    if (i < NUM_LEDS) {
      leds[i] = CRGB::White;
      leds[i + 1] = CRGB::White;
      leds[i + 2] = CRGB::White;
      leds[i + 3] = CRGB::White;
      leds[i + 4] = CRGB::White;
      leds[i + 5] = CRGB::White;
      leds[i + 6] = CRGB::White;
      leds[i + 7] = CRGB::White;
      leds[i + 8] = CRGB::White;
      leds[i + 9] = CRGB::White;
      FastLED.show();
    }
  }
}

Answer 1

You could replace:

leds[i] = CRGB::White;
leds[i + 1] = CRGB::White;
leds[i + 2] = CRGB::White;
leds[i + 3] = CRGB::White;
leds[i + 4] = CRGB::White;
leds[i + 5] = CRGB::White;
leds[i + 6] = CRGB::White;
leds[i + 7] = CRGB::White;
leds[i + 8] = CRGB::White;
leds[i + 9] = CRGB::White;

with:

for (int j = 0; j < 10; j++) {
  leds[i + j] = CRGB::White;
}

Also, you need to change your i < NUM_LEDS into something safer; the loop after it could be going 10 LEDs beyond i and therefore beyond NUM_LEDS.