#define Trig  3
#define Echo  4
#define Led   2
long width, distance;
void setup() {
  Serial.begin(9600);
  pinMode(Trig, OUTPUT);
  pinMode(Echo, INPUT);
  pinMode(Led, OUTPUT);
}

void loop() {
  digitalWrite(Trig, 0);
  delayMicroseconds(2);
  digitalWrite(Trig, 1);
  delayMicroseconds(10);
  digitalWrite(Trig, 0);
  width = pulseIn(Echo, 1);
  distance = width / 58.2;
  Serial.print("distance is: ");
  Serial.print(distance);
  Serial.println(" cm");
  if (distance < 100)
    digitalWrite(Led, 1);
  else
    digitalWrite(Led, 0);
  delay(1000);
}