int ledPin    = 2;
int buttonPin = 7;

void setup() {
  pinMode(ledPin, OUTPUT);
  pinMode(buttonPin, INPUT);
  digitalWrite(ledPin, HIGH);
}

void loop() {
  bool buttonState = digitalRead(buttonPin);
  if ( buttonState == false ) {
    digitalWrite(ledPin, HIGH);
  } else if ( buttonState == true ) {
    digitalWrite(ledPin, LOW);
  }
}