Obstacle Avoiding Car

1const int trigPin = 11;
2const int echoPin = 10;
3const int in1 =  9;
4const int in2 = 8;
5const int in3 = 4;
6const int in4 = 3;
7
8
9void  setup() 
10{
11  pinMode(trigPin, OUTPUT);
12  pinMode(echoPin, INPUT);
13  pinMode  (in1, OUTPUT);
14  pinMode (in2, OUTPUT);
15  pinMode (in3, OUTPUT);
16  pinMode  (in4, OUTPUT);
17}
18long duration, distance;
19
20void loop()
21{     
22  digitalWrite(trigPin, LOW);
23  delayMicroseconds(2);
24  digitalWrite(trigPin,  HIGH);
25  delayMicroseconds(10);
26  digitalWrite(trigPin, LOW);  
27  duration  = pulseIn(echoPin, HIGH);
28  distance = duration/58.2;
29  if(distance<30)
30    {
31      digitalWrite(in1, HIGH); 
32      digitalWrite(in2, LOW); 
33      digitalWrite(in3,  LOW); 
34      digitalWrite(in4, HIGH);
35      delay(1200);
36    }
37    
38  else
39    {
40      digitalWrite(in1, HIGH); 
41      digitalWrite(in2, LOW);  
42      digitalWrite(in3, HIGH); 
43      digitalWrite(in4, LOW);
44    }  
45  delay(0);
46}