(HC-SR04) Ultrasonic Arduino? Easy!

int vcc     = 10;
int trigger = 11;
int echo    = 12;
int gnd     = 13;

void setup() {

  Serial.begin(9600);

  pinMode(echo, INPUT);

  pinMode(trigger, OUTPUT);
  digitalWrite(trigger, LOW);

  pinMode(vcc, OUTPUT);
  digitalWrite(vcc, HIGH);

  pinMode(gnd, OUTPUT);
  digitalWrite(gnd, LOW);

}

void loop() {

  long duration, inches, cm;

  digitalWrite(trigger, LOW); // Make sure trigger is LOW by default
  delayMicroseconds(10);

  digitalWrite(trigger, HIGH); // 12ms pulse on trigger
  delayMicroseconds(12);
  digitalWrite(trigger, LOW); // Back to LOW

  duration = pulseIn(echo, HIGH); // Measuring the length of the ECHO pulse

  cm=duration/58;
  inches=duration/148;


  // Print Data Serial (9600)

  if (cm > 100 || cm<3){     // Range: 3-100 cm
    Serial.println("N/A");
    }
  else{
    Serial.print(cm);
    Serial.print("   ");
    Serial.println(inches);
  }

  delay(100);
}