How to make Car Park Sensor with Arduino

1
2#define trig 12
3#define echo 11
4void setup() {
5
6  pinMode(trig,OUTPUT);
7  pinMode(echo,INPUT);
8  pinMode(5, OUTPUT);
9  pinMode(13, OUTPUT);
10  Serial.begin(9600);
11  
12  
13
14}
15
16void loop() {
17
18  
19digitalWrite (trig,LOW);
20delayMicroseconds(2);
21digitalWrite  (trig,HIGH);
22delayMicroseconds(10);
23digitalWrite (trig,LOW);
24
25
26long  t =pulseIn(echo,HIGH);
27
28long cm = t/29/2;
29
30Serial.println(cm);
31delay  (200);
32
33digitalWrite (13, HIGH);
34  delay (500);
35  digitalWrite (13,  LOW);
36  delay (500);
37
38
39if(cm <= 100 && cm >= 60 ){
40  digitalWrite  (5, HIGH);
41  delay (100);
42  digitalWrite (5, LOW);
43  delay (1000);
44}
45else  if (cm <= 50 && cm >=30){
46   digitalWrite (5, HIGH);
47  delay (100);
48  digitalWrite  (5, LOW);
49  delay (500);
50}
51else if (cm <= 30 && cm >=10){
52   digitalWrite  (5, HIGH);
53  delay (80);
54  digitalWrite (5, LOW);
55  delay (1);
56}
57else  if (cm <= 10 && cm >=0){
58   digitalWrite (5, HIGH);
59  delay (50);
60 // digitalWrite  (6, LOW);
61//  delay (50);
62}
63else {
64 digitalWrite (5, LOW);
65// delay  (50);
66}
67}
68