#include <Keypad.h>

const byte ROWS = 4; //four rows
const byte COLS = 4; //three columns
char keys[ROWS][COLS] = {
{‘1′,’2′,’3′,’A’},
{‘4′,’5′,’6′,’B’},
{‘7′,’8′,’9′,’C’},
{‘*’,’0′,’#’,’D’}
};

byte colPins[COLS] = {5, 4, 3, 2}; //connect to the row pinouts of the keypad
byte rowPins[ROWS] = {9, 8, 7, 6}; //connect to the column pinouts of the keypad
char password[4];
char passwordCorrect[4]={‘1′,’2′,’3′,’4’};
byte ok;
byte i;

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

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

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

if (key){
Serial.print(key);
password[i]=key;
i++;
}

if(i==4){
Serial.println(» «);
for(i=0;i<=3;i++){
if( password[i]== passwordCorrect[i]) ok++;
}
if(ok==4){
Serial.println(«Access Authorized»);
}
else{
Serial.println(«Access Denied»);
}
i=0;
ok=0;

}
}