#define Trig 7
#define Echo 8
#define Led 13
long Width ,Distance;
void setup()
{
  Serial.begin(9600);
  pinMode(Trig, OUTPUT);
  pinMode(Echo, INPUT);
  pinMode(Led, OUTPUT);
}

void loop()
 {
    digitalWrite(Trig,0);
    delayMicroseconds(2);
    digitalWrite(Trig,1);
    delayMicroseconds(10);
    digitalWrite(Trig,0);
    Width=pulseIn(Echo,1);
    Distance=Width/58.2;
    Serial.print("Distance is : "); 
    Serial.print(Distance);
    Serial.println("cm");
    if(Distance<100)
      {
        digitalWrite(Led,1);
      } 
        digitalWrite(Led,0);
    delay(1000);

 }