const int echo_pin=2;
const int trig_pin=3;

void setup()
{
  Serial.begin(9600);
  pinMode(trig_pin,OUTPUT);
  pinMode(echo_pin,INPUT);
}
float read_distance()
{
  digitalWrite(trig_pin,LOW);
  delayMicroseconds(2);
  digitalWrite(trig_pin,HIGH);
  delayMicroseconds(10);

int duration=pulseIn(echo_pin,HIGH);
return (duration)*0.034/2;
}
void loop()
{
  float distance=read_distance();
  Serial.print("Measured distance:- ");
  Serial.print(distance);
delay(1000);
}