// A program to display distance value when the push button is pressed
// Add line no. 7, 11 & 19
int echopin = 2;
int trigpin = 3;
int Time;
int Distance;
 // At line no. 7 create a variable 'buttonpin' with a data type 'int' and store a value '4'.
int buttonpin = 4;
void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
   // At line no. 11 use 'pinMode()' function. Inside the function pass two parameters 'buttonpin' and 'INPUT_PULLUP' \
  pinMode(buttonpin, INPUT_PULLUP); 
  pinMode(trigpin, OUTPUT);
  pinMode(echopin, INPUT);
}

int lastState = HIGH;

void loop() {
  
   // At line no. 19 use digitalRead() function, inside the function pass 'buttonpin' variable and store it in a variable 'value' with a datatype 'int'.
  int value = digitalRead((buttonpin));
  if (lastState != value) {
    lastState = value;
    if (value == HIGH) {
      digitalWrite(trigpin, LOW);
      digitalWrite(trigpin, HIGH);
      digitalWrite(trigpin, LOW);
      Time = pulseIn(echopin,HIGH);
      Distance = Time * 0.0172;
      Serial.println(Distance);
    }
  }
}