Arduino Neopixel basic code

neoexample.ino

#include <Adafruit_NeoPixel.h>
#ifdef __AVR__
#include <avr/power.h>
#endif
#define PIN        8
#define NUMPIXELS 16 // Popular NeoPixel ring size
Adafruit_NeoPixel pixels(NUMPIXELS, PIN, NEO_GRB + NEO_KHZ800);

int pressed = 0;

void setup() {
  pixels.begin();
  Serial.begin(9600);
  pinMode(2, INPUT);
}

void loop() {
  pressed = digitalRead(2);
  if (pressed == 1) { // not pressed
    for (int i = 0; i < NUMPIXELS; i++) { // For each pixel...
      pixels.setPixelColor(i, 0, 0, 0);
      pixels.show();
    }
    Serial.println("Off");
  }
  else {
    for (int i = 0; i < NUMPIXELS; i++) { // For each pixel...
      pixels.setPixelColor(i, 255, 0, 0);
      pixels.show();
    }
    Serial.println("On");
  }
  delay(100);
}