int buttonpin = 12;
int ledpin= 8;
int buttonval;

void setup() {
  Serial.begin(9600);
  pinMode(ledpin, OUTPUT);
  pinMode(buttonpin, INPUT_PULLUP); // Enable internal pull-up resistor
}

void loop() {
  buttonval = digitalRead(buttonpin);
  Serial.println(buttonval);
  delay(0);

  if(buttonval==0){
    digitalWrite(ledpin, HIGH);
  }
  else{
    digitalWrite(ledpin, LOW);
  }
}