#include <NewPing.h>// including Library for ultrasonic sensor

int triggerPin = 4; 
#define echoPin 3
#define maxDistance 400// detect object upto 400cm

NewPing varName(triggerPin, echoPin, maxDistance);
//LibraryName varName(pin nos. or name of the pin nos.)

void setup() {
  Serial.begin(9600);  //buad rate 
}
void loop() {
  delay(300);
  unsigned int dist = varName.ping_cm();
  //ping_cm() is the Library function of NewPing library  
  // 
    Serial.print("Distance: ");

  Serial.print(dist);
  Serial.println("cm");
  delay(500);
 
}