button

int buttonPin =2;
int ledPin=3;
int buttonState;
void setup()
{
  // put your setup code here, to run once:
  pinMode(ledPin,OUTPUT);
  pinMode(buttonPin,INPUT);
}

void loop()
{
  // put your main code here, to run repeatedly:
  buttonState=digitalRead(buttonPin);
  if(buttonState==LOW)
  {
    digitalWrite(ledPin,LOW);
  }
  else
  {
    digitalWrite(ledPin,HIGH);
  }
}