int trigPin=9;
int echoPin=8;
float duration , distance;
void setup() {
  Serial.begin(9600);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);

}

void loop() {
 digitalWrite(trigPin, HIGH);
 delayMicroseconds(10);
 digitalWrite(trigPin, LOW);

 duration=pulseIn(echoPin,HIGH);
 distance=0.017*duration;

 Serial.print("Distance:");
 Serial.print(distance);
 Serial.println("cm");
 delay(500);
}