Ultrasonic distance measurement

const int trigPin=2;
const int echoPin=4;

long duration;
int distance;

void setup() {
  // put your setup code here, to run once:
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  Serial.begin(9600);

}

void loop() {
  // put your main code here, to run repeatedly:

  digitalWrite(trigPin,LOW);
  delayMicroseconds(2);

  digitalWrite(trigPin,HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin,LOW);

  duration=pulseIn(echoPin, HIGH);

  distance=duration*0.034/2;

  Serial.print("Distance:  ");
  Serial.println(distance);
}