<code=cpp>
#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] = {3,4,5,6}; //connect to row pinouts 
byte colPins[COLS] = {7,8,9,10}; //connect to column pinouts
Keypad keypad = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS );
void setup(){
  Serial.begin(9600);
}
void loop(){
  char key = keypad.getKey();
  if (key != NO_KEY){
    Serial.println(key);
 }
}   
</code>