Keypad 4x3

#include <Keypad.h>

const byte ROWS = 4;
const byte COLS = 3;

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

byte rowPins[ROWS] = {2, 3, 4, 5};
byte colPins[COLS] = {6, 7, 8};

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

void setup() {
  Serial.begin(9600);
  while (!Serial) {
    ;
  }
  Serial.println("4x3 keypad ready. Press a key:");
}

void loop() {
  char key = keypad.getKey();
  if (key) {
    Serial.print("Key pressed: ");
    Serial.println(key);
  }
}