#include <Keypad.h>

class KeypadHandler {
private:
  static const uint8_t ROWS = 4;
  static const uint8_t COLS = 4;
  char keymap[ROWS][COLS] = {
    { '1', '2', '3', 'A' },
    { '4', '5', '6', 'B' },
    { '7', '8', '9', 'C' },
    { '*', '0', '#', 'D' }
  };
  Keypad* keypad;
  uint8_t *rowPins;
  uint8_t *colPins;

public:
  KeypadHandler(uint8_t *rowPins, uint8_t *colPins)
    : rowPins(rowPins), colPins(colPins) {}

  void init() {
    keypad = new Keypad(makeKeymap(keymap), rowPins, colPins, ROWS, COLS);
  }

  char getKey() {
    return keypad->getKey();
  }
};

uint8_t colPins[KeypadHandler::COLS] = { 5, 4, 3, 2 }; // Pins connected to C1, C2, C3, C4
uint8_t rowPins[KeypadHandler::ROWS] = { 9, 8, 7, 6 }; // Pins connected to R1, R2, R3, R4

KeypadHandler keypadHandler(rowPins, colPins);

void setup() {
  Serial.begin(9600);
  keypadHandler.init();
}

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

  if (key != NO_KEY) {
    Serial.println(key);
  }
}


void setup() {
  // put your setup code here, to run once:

}

void loop() {
  // put your main code here, to run repeatedly:

}