Ultrasonic Security System

1#define trigPin 2
2#define echoPin 3
3#define LEDlampRed 4
4#define  LEDlampYellow 5
5#define LEDlampGreen 6 
6#define soundbuzzer 7
7int sound  = 500;
8
9
10void setup() {
11  Serial.begin (9600);
12  pinMode(trigPin,  OUTPUT);
13  pinMode(echoPin, INPUT);
14  pinMode(LEDlampRed, OUTPUT);
15  pinMode(LEDlampYellow,  OUTPUT);
16  pinMode(LEDlampGreen, OUTPUT);
17  pinMode(soundbuzzer, OUTPUT);
18}
19void  loop() {
20  long durationindigit, distanceincm;
21  digitalWrite(trigPin, LOW);  
22  delayMicroseconds(2);
23  digitalWrite(trigPin, HIGH);
24  delayMicroseconds(10);
25  digitalWrite(trigPin, LOW);
26  durationindigit = pulseIn(echoPin, HIGH);
27  distanceincm = (durationindigit/5) / 29.1;
28 
29  if (distanceincm < 50) {
30      digitalWrite(LEDlampGreen, HIGH);
31}
32  else {
33      digitalWrite(LEDlampGreen,  LOW);
34  }
35  
36  if (distance < 20) {
37    digitalWrite(LEDlampYellow,  HIGH);
38}
39  else {
40    digitalWrite(LEDlampYellow,LOW);
41  }
42  if (distance  < 5) {
43    digitalWrite(LEDlampRed, HIGH);
44    sound = 1000;
45}
46  else  {
47    digitalWrite(LEDlampRed,LOW);
48  }
49 
50  if (distanceincm > 5 ||  distanceinsm <= 0){
51    Serial.println("Outside the permissible range of distances");
52    noTone(soundbuzzer);
53  }
54  else {
55    Serial.print(distance);
56    Serial.println("  cm");
57    tone(buzzer, sound);
58  }
59  
60  delay(300);
61}