const byte trigpin = 2;
const byte echopin = 3;
unsigned long traveltime = 0;
float distance = 0;
void setup() {
pinMode(trigpin,OUTPUT);
pinMode(echopin, INPUT);
Serial.begin(9600);
}

void loop() {
digitalWrite(trigpin, LOW);
delayMicroseconds(2);
digitalWrite(trigpin, HIGH);
delay(10);
digitalWrite(trigpin, LOW);

traveltime = pulseIn(echopin,HIGH);
distance = (traveltime/2)*0.0343;
Serial.print("distance :");
Serial.println(distance);
delay(500);
}