int ledState = 0;         // the current state of the output pin
int buttonState = 0;      // the current reading from the input pin
int lastButtonState = 0;  // the previous reading from the input pin
int lastDebounceTime = 0; // the last time the output pin was toggled
int debounceDelay = 50;   // the debounce time; increase if the output flickers

void setup()
{
  pinMode(8, INPUT);
  pinMode(2, OUTPUT);
}

void loop()
{
  int reading = digitalRead(8);
  if (reading != lastButtonState)
    lastDebounceTime = millis() % 100000000;
  if ((millis() - lastDebounceTime) > debounceDelay)
  {
    if (reading != buttonState)
    {
      buttonState = reading;
      if (buttonState == 1)
        ledState = !ledState;
    }
  }
  digitalWrite(2, ledState);
  lastButtonState = reading;
}