#include <Keypad.h>

const byte ROWS = 4;
const byte COLS = 4;

char keys[ROWS][COLS] = {
  {'1','2','3','A'},
  {'4','5','6','B'},
  {'7','8','9','C'},
  {'*','0','#','D'}
};

byte rowPins[ROWS] = {19, 18, 5, 17};
byte colPins[COLS] = {16, 4, 0, 2};

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

char regNumber[10]; // Assuming a maximum length of 10 characters for the registration number
byte regIndex = 0; // Index to keep track of the registration number input

void setup() {
  Serial.begin(115200);
  Serial.println("Enter your Reg number using the keypad and press # when done:");
}

void loop() {
  char key = keypad.getKey();

  if (key) {
    if (key == '#') {
      // End of registration number input, print the result
      Serial.println();
      Serial.print("Reg number entered: ");
      Serial.println(regNumber);
      // You can perform further actions with the registration number here

      // Reset for the next input
      regIndex = 0;
      memset(regNumber, 0, sizeof(regNumber));
    } else {
      // Append the key to the registration number
      if (regIndex < sizeof(regNumber) - 1) {
        regNumber[regIndex++] = key;
        Serial.print(key);
      }
    }
  }
}