I did the C++ programm for my robot , the programme here : int trigPin = 9;int echoPin = 10;int enA = 6;int in1 = 4;int in2 = 5;int in3 = 7;int in4 = 8;int enB = 3;void setup() {  // put your setup code here, to run once:  pinMode(trigPin, OUTPUT);  pinMode(echoPin, INPUT);  pinMode(enA, OUTPUT);  pinMode(in1, OUTPUT);  pinMode(in2, OUTPUT);  pinMode(enB, OUTPUT);  pinMode(in3, OUTPUT);  pinMode(in4, OUTPUT);  analogWrite(enA, 150);  analogWrite(enB, 150);  Serial.begin(9600);}void loop() {  long ditance = mesurerDistance();  if (distance > 0 && distance < 20) {    arreter();    reculer();    tournerADroite();  } else {    avancer();  }  delay(50);}long mesurerDistance() {  digitalWrite(trigPin, LOW);  delayMicroseconds(2);  digitalWrite(trigPin, HIGH);  delayMicroseconds(10);  digitalWrite(trigPin, LOW);  long duree = pulseIn(echoPin, HIGH);  long distance = duree * 0.034 / 2 return distance;}void avancer() {  digitalWrite(in1, HIGH);  digitalWrite(in2, LOW);  digitalWrite(in3, HIGH);  digitalWrite(in4, LOW);}void reculer() {  digitalWrite(in1, LOW);  digitalWrite(in2, HIGH);  digitalWrite(in3, LOW);  digitalWrite(in4, HIGH);  delay(500);}void tournerADroite() {  digitalWrite(in1, HIGH);  digitalWrite(in2, LOW);  digitalWrite(in3, HIGH);  digitalWrite(in4, LOW);  delay(400);}void arreter() {  digitalWrite(in1, LOW);  digitalWrite(in2, LOW);  digitalWrite(in3, LOW);  digitalWrite(in4, LOW);  delay(200);}