Integrate a keypad into your arduino project.

				
					#include <Keypad.h>//download the keypad library from your library manager of from the arduino site
#define password_length 8

int RedLed = 13;
int BlueLed = 12;
int GreenLed = 11;
int YellowLed = 10;
int buzzer = A5;

//the few declarations below are needed by the Keypad library to function.
const byte ROWS = 4;//rows of your keypad
const byte COLS = 4;//rows of your columns
char hexaKeys[ROWS][COLS] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};
byte rowPins[ROWS] = {9, 8, 7, 6};
byte colPins[COLS] = {5, 4, 3, 2};
Keypad customKeypad = Keypad(makeKeymap(hexaKeys), rowPins, colPins, ROWS, COLS);


int count_userdata = 0;//this variable will be used to count the number of characters a user inputs
char userdata[password_length];//this array will store the user's input
char master_password[password_length] = "9876543";//this is the password the user has to match up


void setup() {
  Serial.begin(9600);
  //this for loop sets the modes of pins 10 to 13 as outputs. The LEDs are connected there
  for (int a = 10; a <= 13; a++) {
    pinMode(a, OUTPUT);
  }
  pinMode(buzzer, OUTPUT);//the buzzer is also an OUTPUT component
  Serial.println("Hello there, type your password to control the system");
}


void loop() {
  char customKey = customKeypad.getKey();
  if (customKey) {
    Serial.println(customKey);
    userdata[count_userdata] = customKey;
    count_userdata++;
  }

  if (count_userdata == password_length - 1) {
    if (!strcmp(userdata, master_password)) {
      Serial.println("access granted");
      delay(1000);
      Serial.println("LEDs about to dance");
      delay(1000);
      danceLED();
    }
    else {
      Serial.println("Access Deied, try again");
      digitalWrite(buzzer, HIGH);
      delay(500);
      digitalWrite(buzzer, LOW);
      delay(500);
    }

    clearData();//this function is called to clear the data the user previously inputed
  }
}

void clearData() {
  while (count_userdata != 0) {
    userdata[count_userdata--] = 0;
  }
  return;
}


void danceLED() {
  //this is the function that is called when the user succesfully types the right password
  //you can replace it with your own project.
  Serial.println("The LEDs are dancing");
  int p = 10;//this is the number of times the LEDs should dance.
  while (p != 0) {
    for (int i = 13; i >= 10; i--) {
      digitalWrite(i, HIGH);
      delay(150);
    }
    for (int i = 13; i >= 10; i--) {
      digitalWrite(i, LOW);
      delay(150);
    }
    //delay(100);
    for (int i = 10; i <= 13; i++) {
      digitalWrite(i, HIGH);
      delay(150);
    }
    for (int i = 10; i <= 13; i++) {
      digitalWrite(i, LOW);
      delay(150);
    }
    p--;
  }
  Serial.println("LEDs are done dancings, input the password again to see it");
}